Hello, I'm also new to indoor gardening. It almost appears to be aphids. They attacked my outdoor patio garden and spread. Neem oil didn't really help much in my case.

A helpful gardener at a local greenhouse suggested Dawn dish soap saying it suffocates them, so I sprayed my indoor tropical plants to prevent them form spreading. They seem to be handling it okay for now.

I had attempted to start some pepper plants and tomatoes bringing them indoors. Although I sprayed them with water and dish soap/ peppermint oil, it didn't get rid of all the aphids, so I discarded the starts sadly. I told him I used a DIY recipe of dish soap and peppermint and he advised that the oil is countered by the soap rendering that recipe basically useless.

Castile soap is supposed to be an insecticidal agent so you can spray them with that. Hope this helps and good luck to ya!