Is this Kaplan-Meier curve as expected? Survival rates look low to me.

[kitscorp]

Hey, I'm new to survival analyses- sorry if this is an obvious question. I was trying around with generating survival curves in lifelines for a study I'm working on. However, I noticed that the Kaplan-Meier-curves look quite 'pessimistic' given the data, especially when defining an entry point (but even without it). Here is the Kaplan-Meier curves:

https://ibb.co/0VQ9LPL (Kaplan-Meier curve without entry)
https://ibb.co/rx7gjXm (Kaplan-Meier curve with entry)

For some context: The entry age for this study is ~20, and we have data only up to ~age 40. The condition we're looking at should increase with age, but there is a kind of interesting bias in our data, whereby a larger proportion of the older study participants are unaffected. I'm fitting Cox-hazards models (I haven't decided yet whether to try and left-censor it) and wanted to plot Kaplan-Meier curves along with it. Here are some plots of the data itself:

https://ibb.co/1RCk5Ly (Density plot, blue = unaffected, orange = affected))
https://ibb.co/b3J4DsS (Scatter plot, y shows percent of unaffected individuals per age value)

So to my questions: Do the Kaplan-Meier curves look as you would expect?