Why does Google Play Services require so many permissions. Access to my phone, contacts, text messages, camera, microphone, and even body sensors cannot be turned off without constant push notices saying they must be turned on for it to work properly. I didn't know my phone had "body sensors". It is the only app in my phone with such a request. I find all these demands for access to every aspect of my phone way too invasive into my personal information. No possible permission is excluded. Do I have to keep this app running or can I disable it?
Google Play Services is kind of a "service provider" for other apps on your device. A look into our google-play-services tag-wiki will give you some details and explain some of the permissions this app requires. For example it requires access to your location as it offers location services to other apps.
If you'd disable this, several of your apps will probably no longer function the way they did before. Some apps won't care. But especially other Google Apps will complain (Gmail and Google Maps definitely will). As the Settings app is not affected, you can try that out (if the effect is too strong, you can always revert your change).
On the other had, you could also try revoking some permissions from the Google Play Services app, if your Android lets you (it's a system app, so depending on your device and Android version you might not be able to do that).
It is because new android >6.0 ask for permissions on any app ,even on system apps. Don't be scared. Allow them, because it is services for all google apps. Without that youtube ,gmail, chrome won't work. It's neccesary. And because it is neccesary it request a lot. Google wants from you to doenload all their apps to use. And it request contacts and dialing because he want to backup your contact to google servers in case of losing data.