An iPod like interface that many were used to already would seem plausible. Looking back it's easy to see but probably not so much then.
Yep, and I think Jobs (like Ive) tend to like to reuse designs which had already been proven successful.
The iPod was successful, so why not try to keep that style going.
Especially since the primary reason for even doing the iPhone, was to combat other smartphones which were threatening to steal iPod sales in the future. (Same reason the ROKR was done, but with better execution.)
Thus I think in Jobs' mind, at least at first, the iPhone was more an iPod+phone than anything else. I think adding the Web and other apps became important later.