Out of curiosity, I have made a list of (apparent) cognates between modern Italic/Romance languages and modern Celtic languages, using online dictionaries. I purposely chose only "primitive" concepts, for which there would already have been words to express around the time of the Italic-Celtic linguistic split (probably sometime around 1000 BC). Here goes:
We-Welsh, Ir-Irish, Sc-Scottish Gaelic, It-Italian, Sp-Spanish, Pt-Portuguese, Fr-French
Bear: arth (We) --- orso (It), urso (Pt), ours (Fr), oso (Sp)
Dog: ci (We), cù (Sc) --- cane (It), can (Sp), cão (Pt)
Cow/Ox: buwch (We), bó (Ir), bò (Sc) --- mucca, vacca ("cow", It), bue ("ox", It), boi ("ox", Pt), buey ("ox", Sp), boeuf ("ox", Fr)
Fish: pysgod (We), iasc (Ir), iasg (Sc) --- pesce (It), pez (Sp), peixe (Pt)
Goat: gabhar (Ir), gobhar (Sc) --- capra (It), cabra (Pt/Sp), chèvre (Fr)
Horse: cappal (Ir), ceffyl (We) --- cavallo (It), caballo (Sp), cavalo (Pt), cheval (Fr)
Rabbit: cwningen (We), coinín (Ir), coineanach (Sc) --- coniglio (It), conejo (Sp), coelho (Pt)
Rooster: ceiliog (We), choileach (Ir), coileach (Sc) --- gallo (It/Sp), galo (Pt)
Bridge: bont (We) --- ponte (It/Pt), pont (Fr), puente (Sp)
Gold: aur (We), óir (Ir), òr (Sc) --- oro (It, Sp), or (Fr), ouro (Pt)
King: rí (Ir), rìgh (Sc) --- re (It), rey (Sp), rei (Pt), roi (Fr)
Shield: sciath (Ir), sgiath (Sc) --- scudo (It), escudo (Sp, Pt)
Silver: airgead (Ir), airgead (Sc), arian (We) --- argento (It), argent (Fr)
Weapon: arm (Ir/Sc), arf (We) --- arma (It/Sp/Pt), arme (French)
Weight: pwysau (We) --- peso (It/Sp/Pt)
Wheel: roth (Ir/Sc) --- ruota (It), roda (Pt), rueda (Sp), roue (Fr)
(to) Kill: cuir (Sc) --- uccidere (It), akin to suffix -cide
Arm: braich (We) --- braccio (It), brazo (Sp), braço (Pt), bras (Fr)
Body: corff (We), corp (Sc) --- corpo (It, Pt), cuerpo (Sp), corps (Fr)
Leg: cos (Ir), cas (Sc), goes (We) --- coscia ("thigh", It), coxa ("thigh", Pt), cuisse ("thigh", Fr)
Nail: ingne (Ir), ìne (Sc), ewinedd (We) --- unghia (It), unha (Pt), uña (Sp), ongle (Fr)
Tooth: dant (We) --- dente (It/Pt), diente (Sp), dent (Fr)
Sea: môr (We), muir (Sc) --- mare (It), mar (Pt/Sp), mer (Fr)
River: afon (We), abhainn (Sc) --- fiume (It)
Juice: sú (Ir), sùgh (Sc), sudd (We) --- succo (It), suco (Pt), jugo (Sp)
Milk: llaeth (We) --- latte (It), lait (Fr), leite (Pt), leche (Sp)
Day: diwrnod (We) --- giorno (It)
Night: nos (We), oíche (Ir), oidche (Sc) --- notte (It), noche (Sp), noite (Pt)
Morning: maidin (Ir), madainn (Sc) --- mattinata (It), matin (Fr)
God: dia (Ir), dia (Sc), duw (We) --- dio (It), dios (Sp), deus (Pt), dieu (Fr)
Truth: fírinne (Ir), firinn (Sc) --- verità (It), verité (Fr), verdad (Sp), verdade (Pt)
Life: bywyd (We), beatha (Sc) --- vita (It), vida (Pt/Sp)
Dead: marw (We), marbh (Ir), marbh (Sc) --- morto (It/Sp), muerto (Sp), mort (Fr)
People: pobl (We) --- popolo (It), peuple (Fr), pueblo (Sp)
White: bán (Ir), bàn (We) --- bianco (It), blanco (Sp), blanc (Fr)
We-Welsh, Ir-Irish, Sc-Scottish Gaelic, It-Italian, Sp-Spanish, Pt-Portuguese, Fr-French
Bear: arth (We) --- orso (It), urso (Pt), ours (Fr), oso (Sp)
Dog: ci (We), cù (Sc) --- cane (It), can (Sp), cão (Pt)
Cow/Ox: buwch (We), bó (Ir), bò (Sc) --- mucca, vacca ("cow", It), bue ("ox", It), boi ("ox", Pt), buey ("ox", Sp), boeuf ("ox", Fr)
Fish: pysgod (We), iasc (Ir), iasg (Sc) --- pesce (It), pez (Sp), peixe (Pt)
Goat: gabhar (Ir), gobhar (Sc) --- capra (It), cabra (Pt/Sp), chèvre (Fr)
Horse: cappal (Ir), ceffyl (We) --- cavallo (It), caballo (Sp), cavalo (Pt), cheval (Fr)
Rabbit: cwningen (We), coinín (Ir), coineanach (Sc) --- coniglio (It), conejo (Sp), coelho (Pt)
Rooster: ceiliog (We), choileach (Ir), coileach (Sc) --- gallo (It/Sp), galo (Pt)
Bridge: bont (We) --- ponte (It/Pt), pont (Fr), puente (Sp)
Gold: aur (We), óir (Ir), òr (Sc) --- oro (It, Sp), or (Fr), ouro (Pt)
King: rí (Ir), rìgh (Sc) --- re (It), rey (Sp), rei (Pt), roi (Fr)
Shield: sciath (Ir), sgiath (Sc) --- scudo (It), escudo (Sp, Pt)
Silver: airgead (Ir), airgead (Sc), arian (We) --- argento (It), argent (Fr)
Weapon: arm (Ir/Sc), arf (We) --- arma (It/Sp/Pt), arme (French)
Weight: pwysau (We) --- peso (It/Sp/Pt)
Wheel: roth (Ir/Sc) --- ruota (It), roda (Pt), rueda (Sp), roue (Fr)
(to) Kill: cuir (Sc) --- uccidere (It), akin to suffix -cide
Arm: braich (We) --- braccio (It), brazo (Sp), braço (Pt), bras (Fr)
Body: corff (We), corp (Sc) --- corpo (It, Pt), cuerpo (Sp), corps (Fr)
Leg: cos (Ir), cas (Sc), goes (We) --- coscia ("thigh", It), coxa ("thigh", Pt), cuisse ("thigh", Fr)
Nail: ingne (Ir), ìne (Sc), ewinedd (We) --- unghia (It), unha (Pt), uña (Sp), ongle (Fr)
Tooth: dant (We) --- dente (It/Pt), diente (Sp), dent (Fr)
Sea: môr (We), muir (Sc) --- mare (It), mar (Pt/Sp), mer (Fr)
River: afon (We), abhainn (Sc) --- fiume (It)
Juice: sú (Ir), sùgh (Sc), sudd (We) --- succo (It), suco (Pt), jugo (Sp)
Milk: llaeth (We) --- latte (It), lait (Fr), leite (Pt), leche (Sp)
Day: diwrnod (We) --- giorno (It)
Night: nos (We), oíche (Ir), oidche (Sc) --- notte (It), noche (Sp), noite (Pt)
Morning: maidin (Ir), madainn (Sc) --- mattinata (It), matin (Fr)
God: dia (Ir), dia (Sc), duw (We) --- dio (It), dios (Sp), deus (Pt), dieu (Fr)
Truth: fírinne (Ir), firinn (Sc) --- verità (It), verité (Fr), verdad (Sp), verdade (Pt)
Life: bywyd (We), beatha (Sc) --- vita (It), vida (Pt/Sp)
Dead: marw (We), marbh (Ir), marbh (Sc) --- morto (It/Sp), muerto (Sp), mort (Fr)
People: pobl (We) --- popolo (It), peuple (Fr), pueblo (Sp)
White: bán (Ir), bàn (We) --- bianco (It), blanco (Sp), blanc (Fr)