I agree with you that Jobs was never a brilliant engineer, but I don't think Gates was particularly brilliant either and to say Jobs lacked imagination is ludicrous and to say he never invented anything is simply untrue. It may even be true he never invented a circuit (such as the Disk II controller) or never built a prototype himself, but that's not the whole of inventing something.

BTW, it was the Lisa that built upon the Alto (and added quite a bit of very clever ideas that never made it into the Mac).