I believe 'random' is a concept humans have invented to make it easy to deal with observations which have no apparent cause.

I believe all 'random' actions could be explained if you were able to observe enough detail.

Take a dice roll for instance; everyone would agree that is random. What if you knew everything about the situation? The precise shape and size of the dice, the location of all the atoms in the dice, where all the air molecules are and their velocity, etc, etc. If you know all that, then it starts to look quite plausible that the outcome could be known. This level of detail is of course impractical, but it's not impossible, all these things are measurable.