You make it sound so easy, but it really, really isn’t. The majority of the Earth’s population is monolingual because learning more than one language is hard. It’s a lot easier when you’re a toddler, to the point they could legitimately have two native languages, but people rarely learn new languages at that age because few families are bilingual.

And that’s just learning any language. English in particular can be unusually difficult to learn (though it’s not as hard as Icelandic or ideographic languages). Both our grammar and our vocabulary are a weird mishmash of Germanic and Romantic languages, and they also have some weird quirks essentially unique to English. Our pronunciation and spelling is even weirder, especially since the Great Vowel Shift made the way we pronounce vowels drastically different from pretty much any other language that primarily uses the Latin alphabet and since we have so many loanwords which have spellings almost unchanged from their original languages but drastically different pronunciations or vice versa. (Side note: how did we get our current pronunciation of “karaoke”? The original Japanese pronounce it basically how it has been romanized (“kah•rah•oh•kay”), and no other English word pronounces an “a” with an “ee” sound, so what gives? I get why we changed the first “a” to make an “ay” or “air” sound and the “e” to make an “ee” sound, but the second “a”’s sound makes no sense at all.) There’s actually a joke that “fish” can be spelled “ghoti” without changing the pronunciation (“gh” from words like “enough”, “o” from “women”, and “ti” from the suffix “–⁠tion”), and “ough” is pronounced incredibly inconsistently («ou» in “drought”, «ə» in “thoroughly”, «o͞o» in “through”, «ō» in “though”, «ŏ» in “thought”, «ŏf» in “cough”, «əf» in “Greenough”, «ŭf» in “enough”, «ŭp» in “hiccough” (now more commonly spelled “hiccup”), and «ŏk» in “hough” (now more commonly spelled “hock”), with “slough” being pronounced «slŭf», «slou», or «slo͞o» depending on the meaning.

This (mostly) ultimately comes from Britain (where English originates) having been conquered by the Norse and the French early on, which greatly influenced our language to mix the original version we had with numerous Old Norse, French, and Latin words and rules pretty early in the history of Old and Middle English. There was also the fact that, unlike many other languages, there is no “English Authority” or whatever that has official say on what is or isn’t “correct” English. Germany, France, Spain, Japan, China, and several other countries do have regulations or regulatory bodies that dictate one or all of their respective languages’ official vocabulary, orthography (alphabet, abjads (think Arabic), logograms (think Ancient Egyptian hieroglyphs, Chinese characters, or Kanji), syllabary (think the Japanese katakana and hiragana), pictograms, numerals, ligatures, etc.), spelling(s)/writing, punctuation, reading/writing order, capitalization (where applicable), pronunciation(s), grammar, etc. In fact, until Shakespeare’s day, there were essentially no standardized rules for English, and Webster was also one of the first to see any success in standardizing English spellings. This meant a lot of changes to the language that made it more needlessly complicated.

Honestly, the one thing that makes English less complicated than most languages is the lack of grammatical gender in the vast majority of words, and those that have grammatical gender are almost entirely nouns, primarily third-person pronouns, nouns referring to humans as such (“man”/“men”, “woman”/“women”, “boy(s)”, “girl(s)”, “gentleman”/“gentlemen”, “lady”/“ladies”, “guy(s)” (though this is also often used as if gender-neutral), “gal(s)”, “dude(s)” (also sometimes gender-neutral), “dudette(s)”, etc.), words for family members/significant others (“father”, “mother”, “dad”, “mom”, “daddy”, “mommy”, “pa”, “ma”, “papa”, “mama”, “pappy”, “mammy”, “son”, “daughter”, “uncle”, “aunt”, “nephew”, “niece”, “grandfather”, “grandmother”, “grandpa”, “grandma”, “grandson”, “granddaughter”, “boyfriend”, “girlfriend”, “fiancé”, “fiancée”, “groom”, “bride”, “husband”, “wife”, etc.), several occupations (mostly ending in “–man”, “–men”, “–woman”, or “–women”, though there are some others, like “waitress”), titles of nobility/royalty, some prefixed titles (“Mr.”, “Mrs.”, “Ms.”, “Miss”, “Sir”, or “Lady”, but not “Dr.” or “Professor”), and some animals (mostly livestock or hunting targets, like “ram” vs “ewe”, “bull” vs “cow”, “rooster” vs “hen”, “buck” vs “doe”, etc.); in all of those cases, the grammatical gender virtually always refers to actual organisms with actual genders/sexes (use of “she” to refer to vessels and such notwithstanding). German has three grammatical genders (masculine, feminine, and neuter), and France and Latin (along with most Romantic languages) both have two grammatical genders (masculine and feminine) present in every single noun and most pronouns, which is reflected in other words (mostly articles and adjectives, but sometimes verbs are also affected), so it’s kinda surprising how little grammatical gender there is in English.