From NASA: https://www.nasa.gov/audience/forstudents/9-12/features/F_Hu...

"When there is no visual input as is common in many flight situations, we rely more heavily on our vestibular sense for this information. However, in flight and in space, our vestibular system, _which is designed to work on the ground in a 1g environment_, often provides us with erroneous or disorienting information."

We have a system to somewhat understand and orient ourselves in 3d obviously, but it has quirks because evolution tuned it to work best on the ground + assuming 1G of gravity as "down".

Orienting in 3d is not intuitive for us. We can do it but we need a _lot_ of help to do it safely.