So I know you can just make spells for a campaign, but what's the dnd lore for actually making a spell? Like how was firebolt made? How was it found out? Can anybody make a spell with enough "research"? If so how does that research go about? This might not have an answer, but i think for storytelling, and mostly just out of curiosity, i think it would be good to know the lore of spell-making.

Yes, it's possible to create spells. Many spells are named after their inventors: Abi-Dalzim’s Horrid Wilting, Aganazzar’s Scorcher, Bigby's Hand, Drawmij's Instant Summons, Leomund's Secret Chest, Maximilian's Earthen Grasp, Melf's Minute Meteors,Mordenkainen's Magnificent Mansion, Nystul's Magic Aura, Otiluke's Resilient Sphere, Rary's Telepathic Bond, and Tasha's Hideous Laughter to name a few. A lot of these spells were created by Gary Gygax (one of the two creators of the game) for his high-level wizard players in his home campaign.

However, there's no rules for players to create their own spells in 5th edition. That's the kind of thing you'll have to work out with your DM. A good starting point would be the downtime rules in the Dungeon Master's Guide or Xanathar's Guide to Everything. The DMG also has guidelines for DMs to create new spells.

Alright, good to know! and thats given me a fantastic idea! thanks a bunch mate!