The short answer
Separating the message from the messenger is a learnable habit. When feedback arrives, try writing it down before you decide whether to trust it. That small delay stops your credibility filter from running first and lets the content get a fair hearing on its own.
You take in information well — that's not the problem. The problem is that your brain runs a quick background check on the speaker before the words even register. Research on feedback orientation shows that people naturally weight feedback by the source's perceived status or expertise. That's not weakness; it's wiring. But it means a junior colleague, a customer, or someone you barely respect can carry a real signal you'll never pick up because the filter fires too fast.
Marcus writes about not undervaluing yourself to the point of being discouraged from right action. There's a mirror principle here for you: don't undervalue a message to the point of dismissing it before you've tested it. The messenger's rank in your mind is not the same thing as the accuracy of what they said. Those are two separate questions, and right now you're collapsing them into one.
This week, try a simple split. When feedback comes in — from anyone — write down the content first, in one plain sentence, before you think about who said it. Then sit with that sentence for a day. Ask: if someone I do respect had said this exact thing, would I take it seriously? If the answer is yes, the feedback probably deserves a real look, regardless of who brought it to you.