Hi Carime,
Thanks for bringing your question to Disney Parks Moms Panel.
Yes, there are many attractions where a backpack you are carrying around the theme parks can be brought on the attractions with you. Your individual experience will really depend on the size of your backpack.
Attractions that are boat-ride attractions like
"it's a small world" and
Pirates of the Caribbean will have space for you to keep your backpack at your feet. Other attraction ride vehicles have a space or compartment to store your backpack. Still, on other attractions like
Soarin' the Cast Members will direct you to leave your backpack on the floor in a central area near your row.
I typically tour the parks with a small shoulder-strap backpack or draw-string back pack.
Locker rentals are also an option.
Be sure to familiarize yourself with
park rules that include bag check as well.
Enjoy your Disney!
Jerry