Adults should not feel the need to constantly entertain the little ones, and should never use baby voices (these are annoying in themselves, they make it take longer for infants to lean to talk properly, and make children's voices higher and more annoying). I tend to be a calming influence around young children, but I don't like the short attention spans engendered by those constantly trying to arouse a child's interest.
I would not such mind babies as I once was. I always had a long attention span, and was quiet but friendly. I never cried for attention, food, or changing, although i did sometimes cry in the bath due to pain from the soapy water irritating the circumcision. I started speaking at 5 months old, was using complete sentences by 7 months, and while my pronunciation was not yet perfect I was making literary allusions at 9 months old. (The most repeated example is that when I at that age saw my dad running up a hill as part of a marathon I said "Huh, that daddy-man shu-shu twain tink he can," in reference to The Little Engine That Could.) I was strong enough to roll over at one day old, but took a while to develop other motor skills. I did however learn to walk (with a hand on the wall for support) several months before I could crawl.