Which makes more sense when combined with this:
That is correct. Adam Sr. is God the Father, the "character" who was in the garden of Eden, who walked with Adam (Jr.) and who latter begat Jesus. As BY also stated:
How has it transpired that theological truth is thus so widely disseminated? It is because God was once known on the earth among his children of mankind, as we know one another. Adam was as conversant with his Father who placed him upon this earth as we are conversant with our earthly parents. The Father frequently came to visit his son Adam, and talked and walked with him; and the children of Adam were more or less acquainted with their Grandfather, and their children were more or less acquainted with their Great-Grandfather; and the things that pertain to God and to heaven were as familiar among mankind, in the first ages of their existence on the earth, as these mountains are to our mountain boys, as our gardens are to our wives and children, or as the road to the Western Ocean is to the experienced traveller. [JD 9:149]
Notice also that BY proposes that when we become Gods, we too will go to our creations as Adams and Eves (Sr) and beget physical children (Adam and Eve Jr):
After men have got their exaltations and their crowns--have become Gods, even the sons of God--are made Kings of kings and Lords of lords, they have the power then of propagating their species in spirit; and that is the first of their operations with regard to organizing a world. Power is then given to them to organize the elements, and then commence the organization of tabernacles. How can they do it? Have they to go to that earth? Yes, an Adam will have to go there, and he cannot do without Eve; he must have Eve to commence the work of generation, and they will go into the garden, and continue to eat and drink of the fruits of the corporeal world, until this grosser matter is diffused sufficiently through their celestial bodies to enable them, according to the established laws, to produce mortal tabernacles for their spiritual children. [JD 6:275, Brigham Young, August 28, 1852.]