All three are about honoring soldiers who died in battle. (“One of the Earliest Memorial Day Ceremonies Was Held by Freed Slaves”). Two of the views are about opposing combatants in the U.S. Civil War. (The contested Confederate roots of Memorial Day).
Today, in the 20the year of the 21st century, the U.S. teeters back and forth as a politically divided nation. The political issues surrounding Memorial Day play out in numerous and fractional ways.
The third, and currently popular view, honors U.S. soldiers in general. The historical record is skimpy and far from precise. As with all things involving humans, there are conflicting and even contradictory issues. You be the judge.