It is definitely legitimate to read this play as being more about the life cycle than about the clash of cultures, though of course both themes are very apparent in this dramatic work. It is interesting that Soyinka himself argued the play was less about cultural clashes and more about responsibility and the Yoruba world view, which saw life as representing a continuum rather than a direct difference between life and death. For example, in the Yoruba world view, the ancestors are still remembered and this is shown in the egungun celebration, where men dress up as ancestors, showing how greatly they are respected and how they are honoured as guides to the living. In the same way, the not-yet born are also seen as potential ancestors returning to life, and are therefore very important.
One way in which this theme is presented is through Elesin's role of the King's Horseman and having to commit ritual suicide. His role is to commit ritual suicide and thus remind the whole community that life is a continuum and it doesn't end as such with death, in the way that Western thought dictates. Note, for example, what Jane says to Olunde in Scene 4 when he calmly tells her that his father is dead:
How cna you be so callous! So unfeeling! You announce your father's own death like a surgeon looking down on some strage... stranger's body! You're just a savage like all the rest.
What Jane fails to realise is that Olunde is not grief stricken as she would be if her father had died, because in the Yoruba world view, death is not an "end," rather it is just another state that the spirit goes through. Thus it is perfectly possible to view this play primarily as being about life and how it is viewed in the Yoruba world view.