Just to amuse you, I threw the following words together.
Long ago, the word summer referred to an animal used to transport goods. In particular, a ‘pack-horse’.
This was an important animal, and the most important means of transport at the time.
As words do, ‘summer’ slowly became used for other important or significant things.
That period of the year which is warm, dry, and favours outdoor activity, became known as the summer.
The word was used for several other ‘high and important’ items too.
Such as certain stones set high in a wall, which perform a specialised function in construction.
This is all my own take on the word ‘summer’ of course.
I made it up as I went along, basing my ideas on a few distant memories of the meaning.
Ah! Those days at school when there was no covid-19. The summer of our youth?
Anyway, I am sure my ramblings are open to a great deal of correction.