1: And the YHVH appeared to him by the oaks of Mamre, as he sat at the door of his tent in the heat of the day.
2: 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,
3: and said, "My lord, if I have found favor in your sight, do not pass by your servant.
4: Let a little water be brought, and wash your feet, and rest yourselves under the tree,
5: while I fetch a morsel of bread, that you may refresh yourselves, and after that you may pass on -- since you have come to your servant." So they said, "Do as you have said."
He seems to be saying "Lord", not "Lords".
Read Colossians 1:15 and 1Jhn 4:12.
And we see later on that Lot calls the other two as "Lords" in Gen 19:1-2.
You seem to lack the understanding of Sh'ma.
Do you know how to read Hebrew?
And tell me, how is your example suppose to fit better for Sh'ma?
Sh'ma is not saying "only one", it is saying "is one", but how can I blame you for not understanding?
Try clicking on the link I presented above and read it.
Ask any of the Rabbis.