C++20 has some new bit operations that can simplify the code in that header. There’s a feature test macro: __cpp_lib_bitops, so these can be added without breaking code that doesn’t use c++20.
popcount can be used in countNumberOfBits, and countl_zero can be used in findHighestSetBit (for uint32, result would be 32 - countl_zero(n);).
There probably are lots of other math routines that can be simplified with C++20 changes, and with the feature test macros those should also be relatively easy to implement.
I’m putting this message here instead of a pull request in github per instructions on github, but can produce pull request if you wish.