Try to have a look at this thread.... it could be helpful!
You can esimate the average CTR is on propeller via their traffic chart information with some math e.g. take Kenya for example. At time of writing their optimal CPM is 0.277 whilst their optimal CPC is 0.024.
Using the formula (note this formula is an estimate):
CPM = CPC x number of clicks per 1000 views
Plugging in the numbers:
CPM/CPC = 0.277/0.024 = 11.5 clicks per 1000 views = 1.15% CTR
Or you could just look at other traffic source info such as: https://richpush.co/insights/, which shows the data but won't factor in the difference in quality between the 2 source.
And as to your actual question on conversion, I think you need to provide more details on your ad since a generic "You've missed 1 message" will have a higher CTR than a targeted ad that says "If you are a recent mother looking to lose 10 pounds buy this" but you'll probably have a much higher chance of conversion in the latter (assuming your funnel is good).
Do you have more offers that you could split test?
Your ad CTRs look healthy to me, but the offer is not converting.
Are you sending some very general messages?
With more targeted ad you will get lower CTR, but the CR can be higher.
You need to test and find this balance, so you get the most bang for your buck! 
It's quite easy to test this.
Keep the current funnel and just test multiple similar offers with it... if all of them fail, it's a problem of the funnel.
The next thing to figure out will be whether it's the ads or the LP, so add a few more LPs to the rotation to see whether some of them perform better. In case you see some LPs performing significantly better, you would know that the LPs were the problem. In case nothing changes, it should be the ADs, so focus on those next. Just take it one step at a time, do not change both the ads and LPs at the same time, because that would ruing the split test and you wouldn't be able to tell what change helped.
It's also possbile and most likely that more than one part needs to be changed or improved. You can improve the overall performance by using both better ads and better LPs.