You can be helping and serving without having any leadership impact or role. Completely. Overwhelming majority of people who help others or server others are not leaders. Helping and serving others will not put you into leadership position nor proves you are capable of leadership.

And while good leaders help on occasions, they are not serving not the bulk of that role does not consists of helping and serving.

The concept you are looking to read up on is servant leadership. It's entire thesis is that a leader serves those "below" them.

https://en.wikipedia.org/wiki/Servant_leadership

Necessary but insufficient.