Do not uninstall the old Play Store. The new APK will overlay on top of the system app. This is safe and reversible.
Downloading an APK for an older version of Android like 5.1.1 (Lollipop) requires careful attention to compatibility and security. How to Find the Right APK google play store apk download for android 51 1 better
: Select "nodpi" for a version that works on any screen resolution. Verify Version : Look for versions tagged with Android 5.0+ . Step-by-Step Installation Do not uninstall the old Play Store
: The most trusted site for verified, safe Google APKs. You can find variants specifically for Android 5.0+ . google play store apk download for android 51 1 better