The houses deal with mundane affairs, passing circumstances, the ephemeral.
The signs have to do with thee essence, the inherent, the enduring.
The Asc and MC are house-related, thus passing.
It is the Sun which establishes and rules over the ecliptic. All other bodies orbit Sun. Sun is Center, the eternal Fire and Light.
Mostly agree, except that the zodiac is Earth-centered, with a transiting Sun. I see the ecliptic as "belonging" to the Earth itself. Objectively speaking, the Sun's transit is tracking Earth's orbit around the Sun, and the ecliptic is the plane of Earth's orbit, projected out into space.
The Ascendant is the point where the Sun's transiting orbit intersects the Eastern horizon, making it the point of Sunrise, in any given location.