They wouldn't be top of the league. They might avoid relegation.
Arsenal have made a couple of astute signings this year. Odegaard and Zinchenko have made a big difference. Jesus played a part early in the season but he's spent a lot of time injured. The players who are making that team tick every week are not on the whole more expensive than our players. Ben White might be the outlier. Odegaard cost the same as Iwobi. Zinchenko cost a little bit more than Dwight McNeil. Saka, Martinelli and Saliba were not expensive even by Everton standards.
Overall, since Arteta's appointment, they might have spent £100 million more than us. Significant, but nowhere near significant enough to explain the relative performance of these teams. Especially given that they've essentially shipped out well over £100 million's worth of players for free: Auba, Ozil, Lacazette, Pepe, Mkitharyan.