To this, I’ll add that ‘harmlessness’ can only seem like morality (at least, it has been to me)—and Kiman also brought this up above—only if considered from a position of not having already established happiness as no. 1 priority. Without happiness, considerations of harmlessless can easily devolve into moral forcing (at least, it has always for me).
When I’m happy (i.e., not miserable), there is now an “of course” to “yea, I’d want the same for others too” … and here both happiness and harmlessness (two different aspects of the same thing) ‘reinforce’ one another.