Ash-Shams, Ch 91, is part of a triplet of chapters (91,92,93) which are sandwiched between 2 chapters expounding on self and social philosophy (90 and 94). This is why I believe Ch 91-93 are the links with natural metaphors which aid self and social evolution.
Ch 91 stars with 6 verses of natural metaphors. It talks about the sun, the moon, the skies, the earth. These 4 interact to form the day and the night in Vs 5 and 6. These are the dynamics in nature which produce our realities.
Vs 7-10 are the final verses which speak of the soul. It mentions the soul and what shapes it. It receives ilham towards its integrity (i.e. not falling apart) and its disintegration. The one who succeeds is the one who evolves.
91/11-15 brings a surprising thematic change, moving on to the people of Thamood. Why are they mentioned here? Perhaps because of the naaqatallah (Allah’s she camel) which symbolizes a social system designed to carry a community. This she-camel cannot function if the soul (Vs 7-10) is not in control. This is why the thamood society failed. The solution of the thamood society is to go back to the state of nuh (the precursor to the ‘aad and thamood people).