I assume Natural selection is the one that takes more time to happen?
No. Natural selection is the process by which certain modifications to organisms are favored over others through the selection pressures imposed by the environment at large.
Meaning, if a certain modification increases the chances of the organism for survival and reproduction, then those modifications have statistically more chances of being inherited by the next generations and thus spread over the population over time.
If a modification is detrimental / harmful to chances of survival and reproduction, then those modifications have statistically less chances of being inherited by the next generations and thus less chance of spreading over the population over time.
If a modification makes no difference to the chances of survival and reproduction, then it might or might not spread over the population over time (it might piggy back with other modifications that ARE beneficial, or it might disappear in the trail of other modifications which harm survival / reproduction rates)
That is what natural selection does. It works in the "here and now" at all times.
The difference between micro-and macro evolution is about the amount of modifications that are accumulated over time, which WERE selected for by natural selection.
To put it simplistically: the accumulation of 5 modifications over X generations = micro evolution.
The accumulation of 1000 modifications over Z generations = macro evolution.
The difference here is mere volume. The process is the same.
A good analogy is the process of "walking".
After 5 seconds you can take 5 steps and you will have covered a "micro distance" of just a couple meters.
After days of walking, you can also take thousands and thousands of steps and you will have covered a "macro distance" of miles.
But there is no difference in the process. The process is and remains mere "walking". A step is a step. It matters not if you repeat it 10 times or a bazillion times.
It's just that the more you repeat it, the bigger distance you'll cover.
Same with evolution. Every new generation brings modifications and accumulates them with the modifications of the previous generation.
After 5 generations you have accumulated the modifications of 5 generations. Micro.
After a bazillion generations, you have accumulated the modifications of a bazillion generations. Macro.
The process of the one generation remains the same: reproduce, mutate, survive, repeat.
But for me I can’t imagine those differences can go so far as tracing it back to a monkey or whatever is considered to be our ancestor
That's because our brains are used to dealing with days, weeks, months, years. Even decades already become problematic.
In evolutionary changes of this order, we are talking about
millions of years.
This speaks to a limitation of our imagination only.