I was confused on what it really means does it mean the people in the lobby or the people who join to help do the speedrun I say this because I saw a 1p Run (Glitchless - Normal Ending, 1P, No Hardcore in 32m 23s 633ms by Guigui413 - 2nd place) with OTHER people not related to the run and just playing So what does it mean?

Idk it doesn't make any sense to me, I just bought a private server and did my run with a friend.. that was it.

I would assume it's not fair to consider multiple people a 1P run.. because they can kill enemies and help you.