As a Magic player, many family members have given me a booster pack for the holidays, so the excitement you feel when this creature makes contact is apt
No, changelings are not artifact creatures

The List Creatures (13) 1 Ornithopter 1 Phyrexian Walker 1 Mulldrifter 1 Memnite 1 Spellskite 1 Thassa, God of the Sea 1 Artificer's Assistant 1 Sai, Master Thopterist 1 Fblthp, the Lost 1 Emry, Lurker of the Loch 1 The Reality Chip 1 Kappa Cannoneer 1 Forensic Gadgeteer Planeswalkers (1) Lands (30) Spells (55) 1 Sensei's Divining Top 1 Brainstorm 1 Mana Drain 1 Counterspell 1 Mystical Tutor 1 Force of Will 1 Propaganda 1 Sol Ring 1 Fellwar Stone 1 Windfall 1 Serum Visions 1 Brain Freeze 1 Mind's Desire 1 Merchant Scroll 1 Frantic Search 1 Fabricate 1 Arcane Denial 1 High Tide 1 Wayfarer's Bauble 1 Zuran Orb 1 Snap 1 Opt 1 Spellbook 1 Lotus Petal 1 Welding Jar 1 Paradise Mantle 1 Mishra's Bauble 1 Pongify 1 Ponder 1 Bone Saw 1 Spidersilk Net 1 Everflowing Chalice 1 Preordain 1 Mox Opal 1 Accorder's Shield 1 Gitaxian Probe 1 Kite Shield 1 Rapid Hybridization 1 Reality Shift 1 Thought Vessel 1 Cathar's Shield 1 Aetherflux Reservoir 1 Mox Amber 1 Narset's Reversal 1 Mirrodin Besieged 1 Mystic Forge 1 Arcane Signet 1 Witching Well 1 Fierce Guardianship 1 See the Truth 1 Resculpt 1 Rise and Shine 1 Stone of Erech 1 Surge of Brilliance 1 Cyber Conversion The Good Things in Life Are Free When you take a look at my list, you see a lot of zero-cost spells

You can open an additional one as a foil, but its not common to do so
The basic conceit of Yu-Gi-Oh is that you need a minimum of 40 cards in your deck, with an overall maximum of 60
The Strategy You know what you sign up for when you choose Tiamat as your commander