Trying to understand the Quran on it's own without the seerah literature is extremely difficult. Most of the interpretations we have a projection of the seerah literature that comes no earlier than 60 years after Muhammad's death. But the seerah literature is full of holes...
The seerah literature is a construction intended to portray Muhammad in a certain light, sometimes borrowing from Biblical themes:
"Ibn Isḥāq has clearly inserted a biblical archetype into al-Zuhrī’s original story modeling his expanded story of Baḥīrā’s annunciation of the prophethood of Muḥammad on the biblical story of the prophet Samuel’s anointing of David as the next king of Israel (1 Sam.16:15–12)"
To make matters worse, Ibn Ishaq's seerah was lost and we only have edited copies that survive in Ibn Hisham, at-Tabari and other fragments!
"The earliest hadith and sīrah accounts that can be reconstructed generally date from no earlier than sixty years after the death of Muḥammad, and, with very few exceptions, they are not eyewitness reports. Hence, the chasm between source and event is never really eliminated."
"More often, these accounts merely don the guise of eyewitness reports rather than actually preserving them. Even when, rarely, historians unearth records of actual memories of the literal, vernacular sort, one cannot necessarily use them as shelter from historical scrutiny."
"Even today, modern scholars have scarcely begun to imagine what it would be like to read the Qurʾan without the aid of the exegetical and chronological framework of the sīrah-maghāzī tradition."
Quotes From @shahanSean's book. Slightly edited to fit in tweets. Opinions my own. 
