Lots of Disney rides aren't really like other amusement park rides. It's more like: sit in this moving box with seats and watch the scenery. And you can take a baby on those. There are plenty of other things to do, too.
One tip to consider: go to the park in the morning, leave in the afternoon to get a rest/break/nap and get out of the heat, and then go back in the evening.
Oh, and you can avoid lines by making an appointment online or something.