The context shows what the meaning of οἰκουμένη is in any given text.
Luke 4:5. 'Then the devil, taking Him up onto a high mountain, showed Him all the kingdoms of the world in a moment of time.'
Hebrews 2:5. 'For He has not put the world to come, of which we speak, in subjection to angels.'
It is a huge stretch to suggest that either of these refer to the Roman Empire.
Likewise, Matthew 24:14. 'And this gospel of the kingdom will be preached in all the world as a witness to all nations, and then the end will come.' It is an even bigger stretch to suggest that 'all nations' refers only to those within the Roman Empire, unless you have already somehow decided that the 'end' happened in AD 70 and that you have to shoehorn every text to fit your erroneous doctrine.
I believe the shoehorning is done by you. You have dozens of clear statements from our Lord and His inspired disciples that "all these things" Matt 24 would be fulfilled in that generation.It is that preponderance of evidence that guides me in my interpretation of the passages above.
I believe if a new Christian, reading a Bible for the first time, if he were not taught by modern culture to automatically disregard it, would come to the same conclusion.
The many verses ought to guide our understanding of the few that seem - only seem - to teach otherwise.