Plus one on this. If you want to play things note perfect to the original (presuming there is only one version of the original), that's fine, join a band that wasnt the same thing. If someone else want's to play something slightly different than that's also fine. Most audiences would notice or care.
I'm not actively playing at the moment but when I have done "All Right Now" I've not played bass in the verse for the first two, but sometimes put something in the verse after the solo, as a way to build it up a bit. Re the solo in this song, does the gutarist include the guitar bit before the bass joins in or not? - Free recorded it did it both ways, so which is correct?