Nope, you still don't understand the differences between Natural Selection and Mutations. I would suggest that you a little reading and some little researches to understand these two mechanisms.
Plus. I do understand the filter analogy, but you are over-complicating Evolution with irrelevant, non-biological scenarios. The problem with using analogy is that people (authors of the analogies) will often use scenarios that is completely different to what they should trying to explain.
Intelligent Designer do this all the times, including Michael Behe. Instead of trying to explain how the Designer is involve with the design of life (or origin of life), they are make up stupid, irrelevant analogies, eg the Watchmaker analogy, the car design & making analogy, the computer analogy, the mouse-trap analogy, and so on, and on, and on.
While analogies work great for writing poems, writing song lyrics, writing fictions, writing religious texts (eg scriptures), but none of those analogies have anything to do with understanding biology, with understanding the origin of life (eg Abiogenesis, or with understanding how life diversified (eg Evolution).
The main problems with using analogies is the tendency to false equivalence, because when you are using any analogy, you are comparing one thing with something else that's entirely different.
So. If you seriously want to illustrate your points, then use either real examples that actually related to evolutionary biology. Use real evidence and real data, and not some more irrelevant analogies.
Now. Having said all that.
Let see what you got wrong.
You are still mixing the 2 mechanisms.
This time, you are over-simplifying Natural Selection with this latest analogy.
Natural Selection don't do any of this purifying process you are talking about, of separating beneficial mutations and harmful mutations.
The cause and needs for changes, only when some environmental changes in a given location, cause selective pressures to life inhabiting in that location.
In the past, I had often use either the brown bear and polar bear scenario during the glaciation periods (Ice Ages) and the post-glaciation aftermath, or the scenario of different species of tortoises living in different islands at Galápagos.
The bears and tortoises examples, are not analogies. The bears are related, as are the tortoises are related, but over times, they developed different physical traits that help them living in the different locations or regions they were living in.
Lately, I have been using the polar bear example, so today, I will use the tortoises of Galápagos.
The tortoises arrived from South America, some times ago, so I cannot tell you when, but these tortoises populated the number of different islands at Galápagos.
In some islands, are highland, with humid weather and plentiful low lying plants, where leaves from plants are within easy reach. While the lowland islands are dryer, and there are not as many branches with lowlying plants.
The highland islands, the tortoises remained almost virtually unchanged since their arrivals from South America. These tortoises have large dome-shaped shells, and short necks and legs. There were no selective pressures on these large tortoises, so there were no needs for adaption for these tortoises that lived in these selected islands where the environment already suited them.
However, the lowland tortoises were living in environments there food sources are not as easy to come by, because they need to reach for leaves to feed themselves.
Instead of growing larger, which won't help them. They have to adapt to the environment they were given. Tortoises choose mates to have offspring, with smaller shells, but at the same time, choose mates with longer neck and longer necks.
The shape of their shells differed from their highland cousins. The shell is shaped like saddleback, hence the name saddleback shells.
The shape of the shell, not only allow their legs to extend, so they have the advantage of height, these saddleback shell tortoises can allow them to stand on their hind legs, something that no other tortoises can do.
Plus the opening of the shell for their head, allow their necks to crank itself upright, again giving more reach.
The shape of their shells, the lengths of their necks and their legs, didn't just magically appear over night. They occur over some period of time.
The current species on all these islands are actually subspecies (including the tortoises with dome shells and saddleback shells) of the original species, the Chelonoidis nigra.
That Natural Selection at work. The different environments in different islands have impacts on how diverse these tortoises become. A couple of islands are only less than 2 kilometres apart, and yet the comparisons of different subspecies are remarkable. This occur because of geographical isolation from one another, allowing some of subspecies to evolve.