Mycus actively works with humans that prove worthy, blob just doesn’t care because you are less than ants to it. Pretty much anything you could do to get the attention of the blob would simply result it in moving from uncaring to actively hostile. It is not human, it does not think human, it does not feel human, it does not understand human, it does not want to understand human.
Of the three main factions, I believe triffid would be the most likely to agree to neutrality or alliance, followed by the mycus, while the blob is too distant and unfocused to even consider either. Think of humans as a remnant of a supermassive ant colony, triffid as multiple bee/wasp colonies, mycus as combination of mushrooms, mold, and parasitic fungus, and blob as a hurricane. Two of them have possibilities that don’t involve “You just die” but the third you don’t have much option with besides “Don’t get in the way” if you want to survive.