From previous posts, you seem to accept it's been millions of years. Where then, do humans fit in?
I see three choices, maybe you have another:
1. Humans have been around since the start of life millions of years ago.
2. A designer created humans thousands of years ago, after designing animal life millions of years ago.
I assumed you must have hastily pidgeonholed me, from the way some of your responses read.
I'll choose option #4, provisionally, and using an underlying hypothesis which, like evolution, is subject to modification to better fit the body of evidence upon introduction of new data.
4. Designer intelligently approached the problem of terraforming a largely molten water-bearing planet so that it would be conducive to animal life by introducing plant life billions of years ago (various chemical consuming bacteria along with, most notably, cyanophyta). Designer modified (engineered) modern humans from existing material circa 40 to 50 thousand years ago.
I predict that humans will eventually attempt further intelligent modifications on the human design in the future.
Humans have shown no capability to create brand new designs, as yet, but have shown a great capacity for remodeling existing design. The considerable consistency across the designs themselves lend to such modifications being a relatively easy acheivement. Just imagine if evolution theory were entirely correct how divergent life would have gotten from those initial split points billions of years ago. It is beyond belief that only one singular path would be taken from plant to animal life, or that only a single kind of SUPERPARENT species would have emerged to which all animal life owed its heritage, thus accounting for the remarkable underlying consistencies observable between very distinctive animal genomes.
TGAC and UGAC, two simple 64 command sets of base code from which all this diversity and all this replication came from.