Esperanto is not a romance language. It incorporates elements from most european languages families (balto-slavic, germanic, romance), and the grammar is most particularly inspired by slavic languages.

And it was pretty much a goal of its creator to be both familiar and foreign for different european language families, as he had experienced division in Poland between speakers of those different families and wanted to have something more universal to gather them all together.

The vocabulary is primarily from Romance languages, but the whole story is more complicated. From the Wikipedia page: "Esperanto's phonology, grammar, vocabulary, and semantics are based on the Indo-European languages spoken in Europe. The sound inventory is essentially Slavic, as is much of the semantics, whereas the vocabulary derives primarily from the Romance languages, with a lesser contribution from Germanic languages and minor contributions from Slavic languages and Greek. Pragmatics and other aspects of the language not specified by Zamenhof's original documents were influenced by the native languages of early authors, primarily Russian, Polish, German, and French. Paul Wexler proposes that Esperanto is relexified Yiddish, which he claims is in turn a relexified Slavic language,[72] though this model is not accepted by mainstream academics.[73]

Esperanto has been described as "a language lexically predominantly Romanic, morphologically intensively agglutinative, and to a certain degree isolating in character".[74] Typologically, Esperanto has prepositions and a pragmatic word order that by default is subject–verb–object. Adjectives can be freely placed before or after the nouns they modify, though placing them before the noun is more common. New words are formed through extensive prefixing and suffixing."

https://en.wikipedia.org/wiki/Esperanto