Hi Flo, thanks for the question!
The origin of the standard bitsy typeface is a little bit of a mystery. I did not create the standard bitsy typeface, and I'm not 100% certain of its origin. I got the typeface from a professor years ago when I was in college, and he said it was ok to use in bitsy when I asked, although he also could not recall who made the typeface originally. Out of curiosity, I did a little more digging today to see if I could learn anything more, and the closest match I could find online was a font on this site (https://robhagemans.github.io/monobit/#fonts) called "Terminal_Bold_21", which apparently was part of Windows 3.1. It's not exactly the same though, since the bitsy version includes some characters not in this font - maybe it's a variation or altered version.
IANAL, so this is just my non-expert understanding, but I believe that bitmap typefaces are not copyrightable (at least in the US), so it should be free for you to use without a license, regardless of its origin.