I don't understand mortgages at all

So when you buy a 200K house on a 20k deposit, the mortgage say 5% interest rate, but making calculations once the house is paid off, you paid the bank almost 500K

shouldn't mortgages be names 50% interest mortgage loan or something like that?

What am I not getting? Thanks ^{^}

EDIT Thank you so much for the replies, I am actually a +30yo person! And I was interested in buying a house until I started making numbers, I don't have kids nor nephews and nieces, this thread has opened my eyes and I think I won't be pursuing this goal from now on

I know I am very ignorant for not knowing these things but I guess it's better learning now than never

I dont know how to stop the thread