With evolution each generation of offspring is born with a very slight change to their bodies.?

I am not much of a fan of gradualism (individuals in each generation differ slightly from their parents in some sort of directed way). That isn't exactly what we see.

Change is not done at the individual level such as you suggest. Instead, numerous offspring have a variety of slightly different characteristics. The odds of individuals having a given characteristic in each generation change depending on who survives and does not survive to reproduce. The kids remain the kids of their parents, basically the same, but some a little more like mom and others a little more like dad, and each with a different mixture of mom and dad. After a while, certain features from mom or dad start to dominate the population, and certain other features disappear. And lo and behold, many generations later, the kids are not like the great-great-(etc.) grandparents even though they don't have much genetically that the grandparents did not have, apart from a few mutations or changes that may or may not even matter (for the specific situation).

But out kids look pretty much like us, and are pretty much like us, but also just slightly different in no predicable way. Different cookies from the same batch of cookie dough.

It gambles. If it's right then it survives and the next generation is closer to the ideal. If it's wrong, it dies and no more like it are born.

Mutations result from errors during DNA replication.

No! No! No! That is not how evolution works. An embryo does not know anything. If it is an embryo of a sexually reproducing species it will be genetically different from both its parents. This happens for two principal reasons. The first is it will have a unique combination of alleles at its gene loci from its parents. The other is it will have mutations. An individual s genotype combined with its environment results in its phenotype. Natural selection works on phenotypes and as a result it changes the frequencies of alleles within a population. That is evolution. Changes to population genetics and not an individual s genetics. The difference between each one of us and our biological parents is NOT evolution.

The embryo doesn't make a change. The embryo IS the change. The embryo is the cross between the parents. And to expect each generation to have slight changes means the genetic code is mutating very rapidly and you have the concept of evolution incorrectly. In some cases, the change can happen in one generation. The peppered moth in Great Britain is a prime example.

What John said.

But in addition, the foetus doesn't 'know' but the genes it has inherited will govern it's absolute existence as an organism. It's not making changes, the change is the different genes inherited during copulation. Which govern everything from hair colour to what specific enzymes do what. The chsnge is between each generation, not during an individuals life.

But as John said, there is often genetic stability for long periods of time. Like the platypus. If the genome of a species suits it's environment, then the lack of selection pressures won't induce such a noticeable shuffle of genes through successive generations, hence the genetic stability.

The strongest and smartest find way to thrive and multiply while the dumb and weak die before they have a chance to multiply. So the ones with the best genes for survival get passed.

The human race has all but stopped evolving, or will split. All get supported and multiple, sure nutrition and health are better due to our tech. But it isn't only the best gens being passed along now becouse the weaker genes, are propped up.