Thank you for clarifying those misconceptions about what recessive and dominant are getting at. A gene isn’t really dominant or recessive. A phenotype (some trait in the organism like blue eyes or a certain disease) can be dominant or recessive though and results from changes in a gene. The same gene could have many different possible mutations, some with dominant effects, some with recessive effects, or some with no effects, depending on the change in the gene and the phenotype.

To go further on that, many recessive diseases are because just one functional copy of many genes are fine from your body’s perspective. Many recessive diseases are due to loss of function of a gene or its protein product, a gene that for a variety of potential reasons no longer leads to a functional protein. Often your body can get by with just one working gene making protein, though both genes are generally always being transcribed and trying to be turned into functional protein.

One big exception to this is the x chromosome. Males only have one x and have a y instead of a second x. The y is very tiny and has very few genes compared to the x, quite different from other chromosome pairs which generally just have copies of all the same genes on each other. Early in embryo development for xx individuals, one of the x chromosomes is generally inactivated, otherwise xx individuals would have double the gene products of all those different genes compared to males, which the body is not expecting for x genes like it does for all the other genes that have a second copy.

en.m.wikipedia.org/wiki/X-inactivation

If you go even further you also get into the idea of penetrance. A gene codes for a protein, but that protein doesn’t exist in isolation, it interacts with lots of other proteins coded by other genes in the body, plus the environment. So for some genetic changes it might be a 100% chance at leading to a certain phenotype (like a disease or a specific trait), or it could be less, like only 70% or 30% chance or something.