Before modification by Floffe at 16/12/2020 06:43:29 AM
Yours is much better. That is the thing with models, they require simplification.
It would be interesting to relate your numbers to the total population in those age groups. 
Let's use some real numbers, shall we?
I looked at the CDC's website. I took their historic data, which for some reason stopped in 2015, and took their annual IFC numbers from that year as an average year (certainly, compared to 2020 it's going to look average). I combined all deaths from (1) pneumonia and (2) influenza, which the CDC has broken down by 10-year age groups except for under 5s and 85+.
Then I took the same CDC numbers for 2020 for (1) pneumonia (with or without Covid), (2) influenza (with or without Covid) and (3) all Covid cases counted by the CDC.
We can see, by taking 2015 numbers and comparing the combined death totals for 2020, the following data:
Age     2015        2020        
Under 1            293      186
1-4             193     149
5-14        219     216
15-24       495     930
25-34       1033        3301
35-44       1884        7676
45-54       5801        19,745
55-64       13,795      50,533  
65-74       23,251      87,200
75-84       36,774      109,827
85+     56,074      125,701
But let's be thorough here. The 2020 numbers start at February 1 and run through December 9, so we should add 62 days and then multiply the 2020 numbers by 1.1694 just to be thorough (i.e., 62/366 + 1). I'm sure that will extrapolate higher than actual numbers, but we want to be as liberal as possible with these numbers.
The results I got were as follows:
Age     2015        2020  Adjusted      Rate        
Under 1         293     218         74.4% of 2015
1-4     193     174         90.2% of 2015
5-14        219     253         115.5% of 2015
15-24       495     1088            219.8% of 2015 
25-34       1033        3860            373.7% of 2015 
35-44       1884        8976            476.4% of 2015 
45-54       5801        23,090          398.0% of 2015
55-64       13,795      59,093          428.4% of 2015
65-74       23,251      101,972         438.6% of 2015
75-84       36,774      128,432         349.2% of 2015
85+     56,074      146,995         262.1% of 2015 
Your anticipated 100,000 deaths for 50 and under doesn't pan out. We don't even get to half that by adding up to 54. Furthermore, the numbers are showing an excess mortality of approximately 3 times that of a normal year, which is precisely what I have been saying.
You're also seeing, interestingly enough, that the very young have an even lower mortality rate. This is probably because Covid doesn't really affect them, but the increased measures taken to prevent the spread of disease has made them less susceptible to "ordinary" infections.
Moreover, the vast majority of the deaths are in the over 65 crowd, and the over 75 are still well over half the deaths. This is in keeping with the 0.01% IFC rising to 0.4% by the 55-64 range, all the way to the 15% IFC for the 85+. Granted, even in a normal year they seem to have something like a 7% IFC from influenza and pneumonia given that the excess mortality percentage is lower.
Apologies on the failure of the site to render charts. The columns were nicely split when I typed this in.
But in my model, I assumed that 100 million young, healthy Americans would be infected. Currently there are 17 million confirmed cases in the whole population. I think it is a reasonable assumption that without restrictions and social distancing or would spread quite a lot faster, no? (among the part of the population who are young and healthy) 

 
  
  
  
  
 