Well, karna was not rejected by Devi Draupadi. If you are mentioning this verse :
Mahabharata, Adi parva, swyamwara parva, SECTION CLXXXIX
"And beholding the son of Surya--Karna of the Suta tribe--like unto fire, or Soma, or Surya himself, resolved to shoot the mark, those foremost of bowmen--the sons of Pandu--regarded the mark as already shot and brought down upon the ground. But seeing Karna, Draupadi loudly said, 'I will not select a Suta for my lord.' Then Karna, laughing in vexation and casting glance at the Sun, threw aside the bow already drawn to a circle. Then when all those Kshatriyas gave up the task, the heroic king of the”
https://www.sacred-texts.com/hin/m01/m01190.htm
This verse is an interpolation because it contradicts itself :
Mahabharata, Adi parva, swyamwara parva, SECTION CLXL :
Then Arjuna approached the bow and stood there like a mountain. And walking round that bow, and bending his head unto that giver of boons--the lord Isana--and remembering Krishna also, he took it up. And that bow which Rukma, Sunitha, Vakra, Radha's son, Duryodhana, Salya, and many other kings accomplished in the science and practice of arms, could not even with great exertion, string, Arjuna, the son of Indra, that foremost of all persons endued with energy and like unto the younger brother of Indra (Vishnu) in might, strung in the twinkling of an eye.
https://www.sacred-texts.com/hin/m01/m01191.htm
Now BORI has removed the former verse and kept the latter. There is another reason why the second One is more Authentic :
Mahabharata, Adi parva, swyamwara parva, SECTION CLXXXVII :
“Yajnasena always cherished the desire of bestowing his daughter on Kiriti (Arjuna), the son of Pandu. But he never spoke of it to anybody. And, O Janamejaya, the king of Panchala thinking of Arjuna caused a very stiff bow to be made that was incapable of being bent by any except Arjuna. Causing some machinery to be erected in the sky, the king set up a mark
https://sacred-texts.com/hin/m01/m01188.htm
King drupada wanted to bestow Draupadi to arjun, hence the bow was made in such a way that only someone who is as strong as Arjuna can string it, this is reflected in the second verse. Moreover, the same parva that contains the rejection, also says
“Then those princes--Karna, Duryodhana, Salwa, Salya, Aswatthaman, Kratha, Sunitha, Vakra, the ruler of Kalinga and Banga, Pandya, Paundra, the ruler of Videha, the chief of the Yavanas, and many other sons and grandsons of kings,--sovereigns of territories with eyes like lotus-petals,--one after another began to exhibit prowess for (winning) that maiden of unrivalled beauty. Adorned with crowns, garlands, bracelets, and other ornaments, endued with mighty arms, possessed of prowess and vigour and bursting with strength and energy, those princes could not, even in imagination, string that bow of extraordinary stiffness
https://sacred-texts.com/hin//m01/m01190.htm
