My son's six. I got the rules and painted some miniatures (the first in more than two decades!) for his birthday last September. Before that, he'd played Castle Panic, King of Tokyo and Settlers of Catan. I think all the games you mention are more mechanically complicated than SBH, so you'll be fine. Of course, skirmish games are more free-form, but I think that works better with kids anyway: "My guy's going to climb up there and shoot the ogre ..."
For kids, I'd recommend giving them smaller warbands of more powerful characters. These are easier to keep control of. Lizardmen work well, because with Quality of 3 (lower is better) and Combat of 4 (higher is better), they're both brave and tough. And they come in at 52 points, so you can just round off to 50 and work out simple warbands very quickly: six lizardmen for 300 points, etc. Elves are another good one: they have Q2 (the best possible) and C3. One of our favourite 400-point warbands is four elite elven archers and an elven bowmaster (stats from the rosters in the book). The bowmaster can fire multiple shots per turn, so there's a lot of opportunity to massacre opponents gleefully from afar.
One thing that makes the game easy for kids to grasp is the use of measuring sticks rather than tapes (as in these photos - devoid, alas, of much in the way of eye-catching terrain!). This makes movement really simple and intuitive: the figures just "leapfrog" the stick. And the Song of Winds and Water supplement has profiles for dinosaurs, which always go down well ...