Can I still sell a product using Amazon FBA without being trademarked?

Hi! Hoping I can get some info on this:

I have a product listed on Amazon FBA in the US that is not trademarked. I am not using the Brand Registry either, as I think the only way to do so is to be trademarked. I only bought 60 units as I wanted to test this out before trademarking etc. However, I did not realize that the name I chose for my brand and put on all 60 units is a name that essentially limits me to a certain type of product. For example, Lash Star.

My questions:

1. How would you suggest I sell off this product without trademarking? I don’t want to trademark as I don’t want to use the name I started with since it limits me to certain types of products, rather than an array of beauty products that I can later add to my store.
2. Can I still become part of Brand Registry without being trademarked?
3. Is it even still possible to sell under “generic”, or should I just cut my losses and start over learning from my mistakes?

Any advice is welcome! I need help haha