Wanting to play bass is a worthy ambition, but the bass and drums are complexly linked.
it's pitch AND rhythm that matter. Some songs use the bass and the drums as musical glue, while the chords and melody rolls around.
There are loads of great songs being suggested, and some, like Smoke on the Water, appear from the notes to be fairly simple. Trouble is, they're not! There might not be too many, but listen to that song and discover there are loads of small pushes and pulls, and accents that if played straight wreck it.
Have a listen
Have a look on you tube for Black Velvet Bass cover (or similar) and you'll find a really simple song - with a few twiddly bits, and shortcuts to play it in Em because it uses open strings a lot. Almost every single one is different, yet based around the same notes. This for me is the key to good bass playing - some kind of instinct is required and NOT adherence to some set of rules. Many of the Black Velvet covers are played with fingers but very, very differently - even in the way the players hold their basses.
Many guitarist can play bass, and vice versa, but strumming a C or G chord on a guitar is OK for many songs - others need finger picking and weird chord shapes - the sort of stuff bass players have to do. If you have low or zero ability, bass is a tough beast to master, because it needs somebody else to play the chords. To play bass you need somebody else, tracks, MIDI files, or progress is very slow.