Well at one point Paul M. did acknowledge that he wondered who the bassist was that was on all those Motown songs that he would listen to so attentively.
McCartney has also said his bass playing was influenced by Brian Wilson's bass playing with the Beach Boys. Does this mean that Brian Wilson was "behind" Macca's style and therefore his influence as well?
Because that is what you are implying when you continually return to the argument that somehow McCartney ought to be considered "second" in overall influence to Jamerson because he has acknowledged that he admired his work and "took" from it.
Anyway, with regard to that I think McCartney always stated that he was inspired to play more active or busy lines because he heard Jamerson doing that. That doesn't mean he was lifting his playing style...
This argument can go on and on indefinitely and part of it comes down to personal taste / preference so on that level it useless to continue. In any event the '60s were a very open time in the world of music and everyone influenced everyone else.
I admire Jamerson because I am a bass player and his classic "unsung hero" story is one pretty much all bass players can relate to. Plus he was a flat out great player. He, and Bob Babbitt, whose story isn't nearly as tragic as Jamerson's, provided the groove to countless Motown classics. They should, of course, be applauded and appreciated for this because millions of people throughout the world enjoyed their work long before anyone knew who they were, or how these recordings ever came to be (IE. the reliance of session musicians).
And lets be honest here, most of the non-bass playing world still has no idea about them.
We know who they were and what they did because we are bass players. To make a bit of a point here - let's talk drummers for a second. Off the top of anyone's head, who can name the drummer that played on, I don't know -
I Wish it Would Rain, by The Temptations without "googling"? I'd bet more drummers would know before the general public or even bass players and other music geeks (and even then still not that many would - after all it is
drummers I'm talking about here...
).
But - and I am not writing this with any sort of disrespect at all - whereas Motown was a hit making factory that churned at classic after classic, they really specialized only in R&B and Soul. These genres were their bread and butter and they'd have been foolish to deviate from the songwriting approach developed by among others, Holland / Dozier / Holland.
McCartney, during his most influential years with the Beatles never really played any songs that matched those genres, (though they did cover some early Tamla / Motown tunes) even though he acknowledges that he adapted certain elements to his style. So he was able to "take' from them, like everyone who has ever "taken" from anyone else.
Motown's bassists never really played songs in the several different styles the Beatles did so whatever they took from him, which may have been very little, was less apparent.
In the end, I'm sticking with McCartney being more influential simply because he was called upon to come up with consistently interesting bass lines in a far wider range of musical styles (to say nothing of Lennon's knack for writing songs which contain multiple time signatures within them) than pretty much every other bassist of his era. I also think that more musicians and bass players at that time attempted to emulate his playing style than anyone else's simply because more people were inspired to be the "next Beatles" than the "next Temptations" or whomever else were residents of Hitsville, USA.
This is not to dispute Motown's and Jamerson's influence since both were obviously huge. I love all that stuff. But I think both took a back seat to The Beatles and McCartney...
Whatever the case it is in the end it is
all good.
And McCartney is still the richest bass player in the world...
LOL 
