Redpill me and blackpill me on Anal Sex

Is anal sex natural?
If so then I would expect it to not require lube? Is lube necessary? Isn't there like anal mucous like that thing lining the large intestines?

Is it so that the first time it hurts but then the body adapts? Like if you never have walked before it's gonna hurt the first time.
Isn't there like a lot of nerve endings there?

I know that if she eat enough fibres then you wont get any shit on your dick.