Animal shelters: UPDATE!

Elle🎵
I've seen a lot of people posting about animals being given up because they are afraid of them hurting their babies. Most of the replies say not to give it to the shelter because they'll kill the animals. 
What's the point of animal shelters if they just kill the animals? I thought people adopted animals from shelters. I'm confused.
Where do you adopt pets from if they kill them in the shelter?
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UPDATE : THANK YOU so much ladies for answering my question. I had no clue this was happening. I don't have any pets by choice so I never knew. I haven't had a pet since I was like 12 maybe, so if I ever ask a question about animals it's because I'm ignorant and don't know, not because I'm trying to be and asshole 😂 You guys are great, thanks for the help.