There are two main things he wanted to communicate around thistheme.
Firstly, the importance of the elders and the transference ofknowledge from the older generation to the younger. There is theoreticalknowledge, represented by the books at the base of the mural, and equallyimportant, wisdom/experience represented by the old man, upon whose shouldersthe next generation sits.
Secondly, if we are thinking about building a betterfuture for the next generation, or how they need to be best equipped for it, wehave to consider (and improve) our relationship with Nature. So each characterhas an animal element to them (Rhino, African Penguin, and Buffalo) tosymbolize this greater connection to the natural world
Placing the young female character at the top, supported bythe two male characters is intended as an expression of 'the future isfemale', placing woman and girls in positions of leadership, where I believethey are really needed now, and have men actively help place them there andassist in executing their vision.
With the phrase, “It's Up To Us” being held high, as theviewer reads it, it invites them into the movement, to be a part of building abetter future.