Are complex organisms a mistake more than a product of evolution?

This question is based on my admittedly rudimentary understanding of organisms as, essentially, DNA engines. Considering that single or simple multicellular organisms persisted for billions of years, and to this day, without the need to develop complex organic mechanisms to assist in their survival, is it possible that the diversity of life that’s a consequence of sexual reproduction should be better framed as a mistake of asexual reproduction, and that perhaps the best form of life is the simpler forms we “evolved” from?