Symmetric Multi-Key Decryption Is there an encryption decryption scheme in which a group of people are all given different keys, and of which each key can decrypt a file. (I’m not talking about a scenario where a file is encrypted with a single symmetric key, and then the symmetric key is separately encrypted with each individuals public key.)

I’ve read articles about broadcast encryption and multi-trapdoors but I'm unsure if any of these would match the correct scheme so I’m looking for.
You don't have to use any special asymmetric construct. Just give the group keys and encrypt the file with a unique random key and than encrypt the file key many times using the keys of the permitted users. 

You can give each user multiple keys some of them shared by relevant groups. To prevent encrypting a file with too many keys. These can even be done ad-hoc, assuming groups repeat themselves. you can create a group key encrypt it with the keys of the members and reuse it if you want to give that group access to another resource later.