I’ve been playing bass for nearly 2 years. I have an understanding of thirds and fifths. My music theory knowledge is very basic. I rely on bass tab to learn new songs. Is this acceptable or should I be learning more music theory?
I'm sure the fastest/smartest method is a personal choice.
I've always just used my ears.
Monkey see [or in this case hear] monkey do.
Just play it right through a few times, which should give you the gist of it, then in sections to hone in on the tougher bits.
Personally, I have a far better innate ability to hear a note & play it on keyboard or fretboard than I do by first knowing the note name. My ear-to-fret/key is better and a lot faster than my name-of-note-to-fret/key. I also don't really see it pictorially from either staff or tab.
I've been playing nearly 50 years & I'm pretty sure this ability or lack thereof was embedded at least 40 years ago.
Imagine a time before there was tab - or bass tab - freely available to anyone with a computer, laptop, phone, etc.
Imagine not being able to read music - which was available, at a price, but often didn't represent the actual bass lines, etc., too well (bit like some tabs..!?)
Those were the days when some of us played in bands, so we had to get the information from somewhere, or our repertoire was tiny.
We learned to listen to the records (back when), and bit by bit, copied what we heard on them - be it the vocals, chords, bass lines, solos, drum patterns/breaks.
After a while, some of us realised that certain patterns of notes or chords kept cropping up. For instance, a set of notes which was called the pentatonic scale. It became pretty common to hear solos which could be identified as using just those notes - so became much easier to learn - as certain other notes wouldn't be in those solos.
I guess that was the start of knowing some theory - useful theory - and ear-training. It took a while, but because it was the only way at the time, we just got better and better at it.
So, yes, look for patterns, find some theory that will be useful - chord families, what 1,3,5,(7) has to do with bass playing, what a walking bass is, how to recognise chord changes, rhythms, how the bass and drums work as a team. Stuff like that.
But bassically (sic), stop relying on someone else for information that you should be learning to do yourself. Get started, and good luck! Please don't be like a bass guitarist at one audition who was asked what key something was in, so he played a note somewhere on the neck, and said 'this key'. True!
EDIT: you would also benefit greatly from learning to read music. It might not help much right now, but later, when you have been playing a fair while, the propensity to find work as a bassist will be greatly enhanced when you're a reader as well as a busker. Believe me!