It's not a bad start, I personally like going for odd numbers on a few ability scores to round them out with half-feats later but that is just my preference.
I would probably switch Tough for Magic Initiate (Wizard - Charisma) and drop Blessed Warrior for Blind Fighting, being a Human does mean not having Dark Vision, so Blindsight makes up for that in melee attacks. Personally don't think Blessed Warrior is a great choice, 2 cleric cantrips is generally not as good as 2 wizard cantrips... and magic initiative gives you an additional 1st level spell over Blessed Warrior. Tough is still a good choice since HP is good for a tank after all.
Great Weapon Master is a good feat, tho wouldn't be usable with Longsword, also the benefit of Hew will be somewhat limited for a Paladin, since most Paladins like to smite when they critical and if you reduce a creature to 0HP, you need another creature within melee range to benefit from it.
By Heavy Armor, I assume you mean Heavy Armor Master (and not heavily armored), it's an okay feat but not one I particularly rate. If your goal is to just take damage then it can help a lot with attacks for three of the most common damage types. My preference is to kill faster than taking more attacks.
Other feats to consider
=== For spellcasting - Warcaster or Resilient (Constitution)
Warcaster - the ability to perform semantic components without needing a free hand does help paladin (affected core rules spells), advantage on concentration saving throws is good and if you somehow get a good cantrip, the ability to use an attack cantrip in place of an opportunity attack supplies some fun, while debated, it's technically usable on True Strike, Booming Blade and Green-Flame Blade (if you forgo the secondary target). - You'd choose Charisma for the ASI with this.
Resilient (Constitution) - gives you proficiency on Constitution Saving Throws, which also includes concentration saving throws. You'd choose Constitution here.
=== For Melee - GWM has already been covered, PAM, Charger, Mage Slayer, Slasher, Shield Master, Sentinel. - almost all of these would be Strength.
Polearm Master (PAM) - This pairs well with GWM, Reach weapons increases your melee range from 5 feet to 10 feet and this gives you an extra reaction and an alternative bonus action for when you aren't using it for spells or lay on hands. The reaction can be made more likely by using a push weapon such as a Pike.
Charger - by moving up to 10 feet you can get an extra 1d8 damage or an extra 10 foot push, pairs well with a Push weapon like a Pike or Warhammer.
Mage Slayer - Paladin has high saving throws, more so Oath of Devotion who gets good bonuses from Charisma - but even a Paladin still fails some saving throws, Mage Slayer saves you from that one Int/Wis/Cha failure. It also imposes disadvantage on concentration saving throws of your targets.
Slasher - the ability to inflict a 10-foot slow enables you to control some creatures better, pair with a push weapon and you might be able to push some creatures further away from the party than they would want, if you do critical, the target gets disadvantage on attack rolls, which is a nice bonus. If wondering why Slasher over Crusher or Piercer, Crusher is better for crit fishing builds (Oath of Vengeance, Barbarian, Champion Fighter), Piercer is technically more damage but there are better choices for just more damage.
Shield Master - if you decided to go sword and board, Shield Master is an extra push back or prone move, it also allows you to turn half damage to no damage when you make a dexterity saving throw, as a reaction.
Sentinel - gives you two additional ways to get opportunity attacks and all opportunity attacks reduce a creature's speed to 0 if it hits, does not pair with PAM
==== For Utility - Chef, Inspiring Leader, Telekinetic, Telepathic
Chef - more healing from short rests and grants temporary HP from a temporary consumable. Good for rounding out a point of constitution
Inspiring Leader - Grants a significant amount (character level + WIS or CHA modifier) of Temporary HP every short/long rest - taking Charisma, notably does not stack with other members of the party taking the same feat
Telekinetic - the mage hand is nice but not the real benefit, the Bonus Action shove however can be good. Take Charisma
Telepathic - the ability to send messages to your allies secretly is always good, a good DM shouldn't meta-game hostile creature actions/decisions based off of your telepathic communications, also the free casting of detect thoughts can be helpful in some RP situations. take Charisma.
I'd say all of these are good, which ones you choose really depends on what type of Paladin your trying to build and what you want to do with that Paladin.
Looking for thoughts and advice
Level 3
Human (tough. And survival)
Pally: (greatsword, longsword. Athletics and intimidation. Blessed Warrior. Oath of devotion.)
Noble: History, Persuasion, 3 dragon ante, perception, insight and history
Str: 16 con:14, dex 8, int 8, wis 12, cha 16
It's not a bad start, I personally like going for odd numbers on a few ability scores to round them out with half-feats later but that is just my preference.
I would probably switch Tough for Magic Initiate (Wizard - Charisma) and drop Blessed Warrior for Blind Fighting, being a Human does mean not having Dark Vision, so Blindsight makes up for that in melee attacks. Personally don't think Blessed Warrior is a great choice, 2 cleric cantrips is generally not as good as 2 wizard cantrips... and magic initiative gives you an additional 1st level spell over Blessed Warrior. Tough is still a good choice since HP is good for a tank after all.
Were you looking for advice for later levels?
Yes please. <3
I am looking at both heavy armor and great weapon Mastsr feats.
Great Weapon Master is a good feat, tho wouldn't be usable with Longsword, also the benefit of Hew will be somewhat limited for a Paladin, since most Paladins like to smite when they critical and if you reduce a creature to 0HP, you need another creature within melee range to benefit from it.
By Heavy Armor, I assume you mean Heavy Armor Master (and not heavily armored), it's an okay feat but not one I particularly rate. If your goal is to just take damage then it can help a lot with attacks for three of the most common damage types. My preference is to kill faster than taking more attacks.
Other feats to consider
=== For spellcasting - Warcaster or Resilient (Constitution)
Warcaster - the ability to perform semantic components without needing a free hand does help paladin (affected core rules spells), advantage on concentration saving throws is good and if you somehow get a good cantrip, the ability to use an attack cantrip in place of an opportunity attack supplies some fun, while debated, it's technically usable on True Strike, Booming Blade and Green-Flame Blade (if you forgo the secondary target). - You'd choose Charisma for the ASI with this.
Resilient (Constitution) - gives you proficiency on Constitution Saving Throws, which also includes concentration saving throws. You'd choose Constitution here.
=== For Melee - GWM has already been covered, PAM, Charger, Mage Slayer, Slasher, Shield Master, Sentinel. - almost all of these would be Strength.
Polearm Master (PAM) - This pairs well with GWM, Reach weapons increases your melee range from 5 feet to 10 feet and this gives you an extra reaction and an alternative bonus action for when you aren't using it for spells or lay on hands. The reaction can be made more likely by using a push weapon such as a Pike.
Charger - by moving up to 10 feet you can get an extra 1d8 damage or an extra 10 foot push, pairs well with a Push weapon like a Pike or Warhammer.
Mage Slayer - Paladin has high saving throws, more so Oath of Devotion who gets good bonuses from Charisma - but even a Paladin still fails some saving throws, Mage Slayer saves you from that one Int/Wis/Cha failure. It also imposes disadvantage on concentration saving throws of your targets.
Slasher - the ability to inflict a 10-foot slow enables you to control some creatures better, pair with a push weapon and you might be able to push some creatures further away from the party than they would want, if you do critical, the target gets disadvantage on attack rolls, which is a nice bonus. If wondering why Slasher over Crusher or Piercer, Crusher is better for crit fishing builds (Oath of Vengeance, Barbarian, Champion Fighter), Piercer is technically more damage but there are better choices for just more damage.
Shield Master - if you decided to go sword and board, Shield Master is an extra push back or prone move, it also allows you to turn half damage to no damage when you make a dexterity saving throw, as a reaction.
Sentinel - gives you two additional ways to get opportunity attacks and all opportunity attacks reduce a creature's speed to 0 if it hits, does not pair with PAM
==== For Utility - Chef, Inspiring Leader, Telekinetic, Telepathic
Chef - more healing from short rests and grants temporary HP from a temporary consumable. Good for rounding out a point of constitution
Inspiring Leader - Grants a significant amount (character level + WIS or CHA modifier) of Temporary HP every short/long rest - taking Charisma, notably does not stack with other members of the party taking the same feat
Telekinetic - the mage hand is nice but not the real benefit, the Bonus Action shove however can be good. Take Charisma
Telepathic - the ability to send messages to your allies secretly is always good, a good DM shouldn't meta-game hostile creature actions/decisions based off of your telepathic communications, also the free casting of detect thoughts can be helpful in some RP situations. take Charisma.
I'd say all of these are good, which ones you choose really depends on what type of Paladin your trying to build and what you want to do with that Paladin.