Proudly

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late Old English prūt, prūd ‘having a high opinion of one's own worth’, from Old French prud ‘valiant’, based on Latin prodesse ‘be of value’. The phrase proud flesh dates back to late Middle English, but the sense ‘slightly projecting’ is first recorded in English dialect of the 19th century.

wiktionary

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From Middle English proutly, proudliche, prudeliche, prudliche, prouteliche, from Old English prūtlīċe, equivalent to proud +‎ -ly.

etymonline

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proudly (adv.)

late Old English prutlice "arrogantly, haughtily;" from proud (adj.) + -ly (2). Meaning "with lofty mien or conscious honor" is attested by 1753.