>:D

Can this locate any kind of creature, or must it be of the Beast category?

5e is generally supposed to be pretty cut and dry interpret it exactly as it is written and while sometimes things are still unclear this seems fairly simple to me it must be a beast or a plant because that is all that the spell dictates. Further evidence of this is the fact that there is a locate creature spell which would be seemingly useless is this lower level spell could do the same thing. 

Quote from DthCb4Chuwe >>

there is a locate creature spell which would be seemingly useless is this lower level spell could do the same thing. 

 Locate Creature can find a specific, unique individual, unlike this spell.

It's even more specific: ANIMALS.

So yes, only mosters belonging to the Beast category.

Can this spell locate plant creatures?

Quote from hatman_0829 >>

Can this spell locate plant creatures?

 Yep, they are a plants, just like beast creatures are beasts.

Sounds faster than a survival check to forage but is it worth a 2econd level spell slot?

It is a ritual spell so you can just cast it as a ritual and it will let you save the spell slot

Quote from DahliaFairchild >>

Sounds faster than a survival check to forage but is it worth a 2econd level spell slot?

 It would be a bit of a waste to use it to forage or hunt, so a waste of a spell slot. That would be like using Fireball to start your camp's bonfire.

The intended use is really to find enemy creatures e.g. the hiding place of the Wolf pack you're tracking, or the nearest Treant hiding in the forest, etc. For that purpose, it's definitely worth a spell slot.

How about using the spell to find a beast you want to study and wildshape into?

 I'm certain the intended use is to do what you say as well as foraging. Especially considering the flavor of classes that can access the spell and that it can be cast as a ritual. If you think the druid or ranger isn't out there using their magic to forage. It would take an entire Long Rest if not longer to do what the spell can do in an hour and cost zero slots 

It's a ritual though. Use it for finding Beasts to wildshape into, Animals to Charm with Animal Friendship to help you with tasks, or get information via Speak with Animals, animals to hunt for food, and animals to use in conjunction with Animal Messenger. Plants could be anything from basic cooking to herbs for healing potions or a specific flower that is the Mcguffin of a quest, or even a Tree suitable for Transport Via Plants (or as I like to call it, Treelaportation)

Also, if you even come across a "rare plant/herb/fungus/whatever can be located with this spell, but isn't common in most areas" and you have a bag of holding or Handy Haversack, just grab a bunch and give it to party members or someone of importance. If you lose track of anyone, just have whoever is still with you toss their sample in the bag so it's not on the same plane, and then you should be able to track down any remaining samples within 5ft.