There was no design for living creatures, no plan, and no end in mind. Evolution changes inherited characteristics of biological populations over successive generations.
Evolution is an opportunistic system; those that survive by advantage or luck, breed another generation. Evolution is chaotic, it is not an aim toward a goal; natural selection by the most adaptable of species within each ecosystem or environment survives.
There is nothing within nature that points that what is is the only way thing could be, quite the opposite in fact. There are many more ways for things to not end up as they are now.
OneZoom Tree of life Tutorial Video