They listen when she's sad, throw her surprise birthday parties, stay up late telling scary stories on Halloween -- the toys are her friends. They even help Bonnie with her homework. As Bonnie learns about the world through textbooks, the toys do the same. They've lived in this world for years, but they've never learned much about it. Every concept Bonnie learns is also new to them, like the ideas of basic civil rights and freedom. When Woody hears this, he has a realization -- toys aren't free. So, he sets out to change that by becoming the poster boy for toy acceptance.
It's the struggle of trying to find your place in a world that is terrified of you, doesn't take you seriously, or flat-out doesn't believe you're real. It's also a story about how the intolerance of older generations gives way to the acceptance of younger generations. Bonnie clearly loves her toys and isn't bothered in the slightest by this major development, but her mom and parents around the world are losing their shit watching toys come to life, all fearing a Chucky pandemic.
"C'mere, you little shit! I wanna play with you!"
For decades, or maybe centuries, toys have been alive and, as far as the movies tell us, they mean no harm to children (unless you're a dick kid like Sid). Apparently, in the Toy Story universe, whatever magic (or whatever you want to call it) gives the toys life also makes them unable to mistreat children. The overall message of the movie, and of the series as a whole, really, is that toys are pure unconditional love. They don't care who you are, they just want to play. If you respect them, they'll respect you. For a very long time they've respected us, and now they want some respect in return.