What's the exact significance of Android NDK platform version compared to API level?

Question

I have an Android app with minSdkVersion.apiLevel set to 18 targetSdkVersion.apiLevel set to 23. Accordingly I set the NDK platformVersion

Answer 1

This is exactly what will happen to your shared library when you install it on android-20 or earlier: it will fail to load. You should not be surprised that signal was missing: Android runtime was never intended to run command-line tools like curl.