Henry actually assisted even more (winning penalties = transfermarkt assists), making it 24G/25A that season in the PL alone for Arsenal. It was his peak season in numbers and he had a pretty decent crew around him (Pires, Bergkamp, Wiltord, Kanu, Vieira, Gilberto, Ljungberg and Edu among others). He was involved in 55% of Arsenals goals in the games he featured in all comps that season (a feat he never repeated or were close to again).
Compared to Haaland's production it is still a way to go though.
Here's all Henry's season for Arsenal in all comps:
99/00 - 26G/9A in 47 games (3311 minutes) - 127 min/G and 95 min/G+A
00/01 - 22G/11A in 53 games (4069 minutes) - 185 min/G and 123 min/G+A
01/02 - 32G/9A in 49 games (4128 minutes) - 129 min/G and 101 min/G+A
02/03 - 32G/28A in 55 games (4638 minutes) - 145 min/G and 77 min/G+A
03/04 - 39G/15A in 51 games (4459 minutes) - 114 min/G and 83 min/G+A
04/05 - 30G/15A in 42 games (3680 minutes) - 123 min/G and 82 min/G+A
05/06 - 33G/10A in 45 games (3773 minutes) - 114 min/G and 88 min/G+A
06/07 - 12G/6A in 27 games (2220 minutes) - 185 min/G and 123 min/G+A
Compared to Haaland this season:
22/23 - 51G/8A in 45 games (3497 minutes) - 69 min/G and 58 min/G+A
Haaland has since the start of the 18/19 season contributed to 52% of his teams goals in games he has featured (1,26 non penalty G+A/90 avg.).
Henry contributed 48% of his teams goals in games he featured in his 5 peak years (0,931 non penalty G+A/90 avg.)