ptysbilbo
Firstly RTMP is a protocol and it 's format was open sourced years ago.
It is based on an older protocol RTSP, which is still used widely.
I think you may be confusing RTMP as a playback format and RTMP as a first leg protocol for broadcasting a live stream.
For example Facebook Live uses RTMP from a user's camera up to their servers. It then encodes this into HLS, DASH etc to be played by the user's watching the stream.
The AWS cloudfront page is related to TV companies distributing VOD and Simulcast streaming via their CDN. It is not the same as what you mention which is more related to services for users live streaming from their phones.
Unless things have changed recently I have never heard of HTTP being used to do the first leg (camera to server)
It is usually offered in the following realtime protocols: WebRTC, RTSP, RTMP