When I was little, my brother and I went through BB guns pretty quickly. None broke that I can think of, but we wanted something cooler every once in a while and they were cheap enough that we could afford to buy them. We started off with Daisy lever-actions which are super basic, but effective. Just make sure the kid can cock it himself. After that, I had one that looked like a miniature shotgun and you had to pump it in the same way. Super difficult for a little guy to do, I usually had to ask for help. Wasn't too fun, either. Then, we graduated up to the ones that you pump the handguard several times. I believe mine was a Daisy also. Those were by far the most accurate, and the first few pumps are easy. They also accept co2 cartridges a lot of the time. These may be too long for a seven-year-old?
Hope this helps.