Did the concept of the Blessed Trinity appear in Genesis?

The Genesis story today is very appropriate for the occasion.
And the LORD appeared to him (Abraham) by the oaks of Mamre, as he sat at the door of his tent in the heat of the day.
He lifted up his eyes and looked, and behold, three men stood in front of him. When he saw them, he ran from the tent door to meet them, and bowed himself to the earth (Genesis 18:1-2)
Can Genesis 18:2 be a prooftext for the concept of the Blessed Trinity? I am afraid the matter is far from so simple. The outcome might be worse.
Throughout history, polytheism was the norm. There was a god to explain this phenomenon, another to take care of that. But things were not of equal standing. Some were surely more important than the others. Gradually, with the rise of some sort of chieftains, ancient people would project this kind of leadership among the gods. Some gods were more powerful than others. Gods were not of equal strengths. So, the idea of the God of gods, the Lord of lords would emerge (Psalm 136:2-3). He would be the Creator God of everything. Some civilizations took another path. They had two gods instead of one to explain the coexistence of good and evil in the world.
When God created man in Genesis 1, the plural case is employed.
Then God said, "Let us make man in our image, after our likeness; and let them have dominion over the fish of the sea, and over the birds of the air, and over the cattle, and over all the earth, and over every creeping thing that creeps upon the earth." (Genesis 1:26)
Isn't it amazing to find the monotheistic God referring to Himself as an "us"?
Scholars prefer to speak of "royal plurality". Kings and queens address themselves in plural, embodying the whole nation. That might not be the intention of the author of Genesis. But we will never know for sure. Some scholars prefer to include angels. That is more acceptable for me. But personal tastes do not dictate the truth. Personally, I prefer an evolutionary approach. Monotheism did not come into existence out of the blue. There are many passages in the Old Testament mentioning the existence of other gods. The existence of these gods is not denied. Yet, Yahweh is the God of gods. The Bible champions monotheism. It triumphs over polytheism.
When God appeared as three men in front of Abraham, it showed that Yahweh leads a community life. We have to wait until the apostolic age to know that the Father, the Son and the Holy Spirit resides in the Godhead. Sorry for the language. I will study theology and will understand and speak more correctly the properties of divinity. Be patient with me.
Today was a day of great festivity in our parish. We celebrated the Diamond Jubilee of the ordination of Fr. Lejeune, the Pearl Jubilee of Fr. John Baptist Kwan and the Silver Jubilee of Fr. Patrick Sun, a total of one hundred and fifteen years of priesthood! In their homilies, they all thanked God for the grace and blessings He had showered on them. They also thanked the congregation for their support so that their priesthood had been made possible and successful. The two "younger" priests thanked Fr. Lejeune for his generous mentorship. When they were newly ordained, they worked as assistant parish priests under Lejeune. They admitted that these early years of priesthood formation were very essential for their later years as parish priests. God has so arranged that they come together in Tuen Mun to serve this community. Fr. Patrick quoted a verse from the Psalm to express the joy of their life together.
Behold, how good and pleasant it is when brothers dwell in unity! (Psalm 133:1)
Life in the priest quarter is always fascinating to outsiders. But Fr. Lajeune is always the grandfather of our parish. His mere presence is enough to spell peace. But this peace has not come easily. The career of Fr. Lejeune is colourful, to say the least. His ambition was to become a missionary priest and was sent to some minority tribes in Northern Vietnam. He was expelled by Communists to the Chinese communities in South Vietnam. At the collapse of the Saigon regime, he was expelled again and ended up becoming a parish priest in Hong Kong ever since. He patiently accepts this arrangement of God and appreciates the value of services in the parishes. Personally, Fr. Lejeune has been an inspiration for me. I also owe him a teaching contract in Shung Tak after leaving La Salle. He is humble in a dignified way.
Fr. John Baptist Kwan has been a very capable parish priest, a perceptive administrator. He will be leaving for St. Margaret parish in Happy Valley. Fr. Patrick Sun is academic as well as spiritual at the same time. He identifies himself with the underprivileged and discovers his call to serve their needs in our community.

Dear Lord, bless all priests, especially the three of them. They have worked very hard to build up a lively parish life among us. I entrust them to Your loving care. Amen.