My friend, nothing but respect here. I don't expect to change your mind but good to exchange ideas on the off chance it makes you think about something. To the issue.

I think there is a fundamental MODALIST presupposition you have about the trinity that you are not getting past. I feel it very strongly in your points. Again, there is nowhere in scripture that teaches the Father, Jesus and the Holy Spirit are one and the same PERSON, it's just not there. However, they are all individually distinct persons but divinely the one God, again it's three PERSONS, ONE ESSENCE. For example riddle me this,

Genesis 19:24
[24]Then the Lord rained brimstone and fire on Sodom and Gomorrah, from the Lord out of the heavens.

How is the Lord raining fire from the Lord out of the heavens??

Or again,

Psalms 45:6-7
[6]Your throne, O God, is forever and ever; A scepter of righteousness is the scepter of Your kingdom.
[7]You love righteousness and hate wickedness; Therefore God, Your God, has anointed You With the oil of gladness more than Your companions.

How can God have a God?

These sort of scriptures (and believe me there are hundreds of these) makes no sense outside for example a trinitarian framework. Unless there are multiple persons who are all ONTOLOGICALLY God.

So far from being mental gymnastics, the trinity (or a multiplicity of persons in the One God) is precisely how God has revealed Himself in scripture from Genesis and as such as is my earlier point, "US" makes perfect sense as a personal pronoun.