When it comes to playing jazz walking bass lines on piano, sometimes simpler is better. This will come as good news to you if you're learning to "walk the bass" with your left hand and feel like your bass lines aren't fancy or complex enough. They probably are.
As a pianist, your bass lines don't have to be as intricate as a bass players' would be. This is partly because we pianists also have to play something with our right hands. We can't give the bass line 100% of our attention like a bass player can! So we do what we can in the left hand, and it blends into the overall sound of the piano, which is relatively homogeneous. The listener doesn't hear as much of a timbral distinction between the chords and bass line as they do when a separate instrument is walking those lines. They hear the pulse, the harmonic outline, and snippets of bass melody.
So enjoy what you can play in the left hand, and gradually add to your repertoire of ways to get from one chord to the next. If you feel your bass lines are too bland, add a chromatic approach note here and there, and maybe even some 8th notes for rhythmic interest. The important thing is to enjoy playing while you keep experimenting with different melodic and harmonic devices. Rest assured that simple bass lines work extremely well on piano since you're also adding rhythmic and harmonic complexity with your right hand. At times, yes, you can "go for it" and pretend you're Ron Carter or some other extraordinary bassist. Most of the time, though, remember that it's the combination of hands that matter in jazz piano.
So play bass lines on lots of tunes, and keep listening to where the lines are going. You'll keep improving as you become more and more confident, without always striving for complexity. Have fun "walking that bass!"
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