For additional context, I was planning to replace the flooring with new vinyl sheets. Was hoping I could remove whatever glue I could with a scraper, and then just spread adhesive right over the remainder old glue to put the flooring down

That's the old glue...I believe it will wash off....or you can glue oevr it.

There is some glue on there and ?paint? It is hard to say whether or not the blue stuff is paint or if it is old glue.

The only way to know for sure if you have asbestos or lead is to send a sample for testing. The only thing I'm worried about is the 'blue' stuff that is sitting on there. The other gunk is glue from the vinyl you are pulling up.

Ah so that looks blue in the photos but is actually black. There is no paint on these stairs. Anyone know if it’s safe to not scrape and just put new glue down? If the black stuff is asbestos I don’t want to disturb it

Never heard of black asbestos glue. And scrap[ing and washing asbestos doesn't raise the dust that is harmful....just don't sand anything asbestos.
I grew up in a house with the hot water pipes wrapped in asbestos, and my mother used asbestos hot pads to set a dish on from the oven, and I spent many years with asbestos tiles on the floor. I will be 84 in 3 weeks.
Just don't raise a dust!

Thanks for the input..I was thinking it could be black mastic glue. Anyone with experience?