I have no idea what thanksgiving meant hundreds of years ago. I’m aware that the natives and colonizers did not get along great back then but that has nothing to do with thanksgiving today.

Today, its generally about getting together and having a nice meal and giving thanks (being positive).

Also, the day being worthless for you, only affects you. It still has worth for everyone else who assign it worth. You haven’t stumbled upon some universal fact, its just an opinion.

You likely could find people who share your opinion and get together with them and all have some sort of Thanksgiving group debate if you’d like.