I don’t see why it’s difficult for an average person to grasp the concept of evolution which is by many means one of the easiest things to understand in science. I am going to help you with this simple analogy, if you still do not understand it then I don’t know how else to help you.
Evolution is like wanting to building a house and then you tell yourself that every year you are going to make a random change to this house in terms changing the paint, facades or even adding more deckings etc. For someone who will be there to observe the house in the every years, the house will evident not change a lot to him because the person is observing the change by bit, the house will still be very recognizable.
For an observer who was there when you newly built the house and then probably travelled to Europe and comes back after 40years when you have made 40 Remodifications, added more decking, balconies, windows etc, that person can argue that you demolished the former building and then erected a new one . The concept of yearly Remodifications may not come to him at first after making an observation.

This exactly how evolution works, the yearly modification in the building analogy is what happens every time genetic materials are inherited by offsprings. It happens inform of recombination of DNA and mutations and errors during gene replication. This the reason why an offspring of any species will not have an exact genetic makeup as the parents, it’s the reason why you cannot exactly look like any of your parents.
If you observe this Remodification for few years, you may not observe any substantial change, however fast forward to say 100,000 generations of constant Remodifications, you will observe a substantial change in the species’s phenotypic looks and forward to 1million generations, you may observe that that a new species is no longer genetically compatible with their ancestors 1million generations ago. Just the same way someone who came back after 40years will argue that this is a new building , we have seen this evidence in fossil records. The random selection of the genes that will survive to the next generation is done by the environment which explains natural selection.

It’s quite easy to grasp and I don’t really know why it’s hard for a lot of people to understand.