It was a lot of work, and it was hard to correctly attribute everything when the places I downloaded the assets from hardly had them in legibly understandable in the first place. I simply compiled what was already there. 

However, I have gone through and despite the lack of attributions and readability in most credit files tried to lcoate all the original assets to try to get a more cohesive attribution list. However, some are still missing,  But as you can imagine, it's quite a large puzzle that is not easily put together.

I'll be honest, I'm not entirely positive how the adding licences for works actually work, so I went through and added more to the download page to try to cover them all and have started notating on the attribution files what was specified on some artists pages from where their work was downloaded. Not all of them are marked yet, but it is a work in progress.

I hope this addresses your issue and at least shows that no harm was intended; if you happen to notice any misattributed aspects or know where some of the missing attributions are from, please feel free to point me in the right direction.