Carbon can be thought of as hybridized sp, as in acetylene where the bond angles are 180, sp2, as in benzene (120) or sp3, as in methane, (109.5).

The oxygen in water has 2 lone pairs and two protons around it so it’s best to think about it as sp3 hybridized. The lone pairs repel a bit more than the protons do, squeezing the bond angle a little bit below 109.5, to like 104.

But yes it’s always flexing and such at room temperature. Also, the protons are constantly exchanging, so any one distinct water molecule has a pretty short “lifetime.”