Beal has missed four games with toe and fibula injuries.
The Wizards have lost three straight games for the second time in just over a month.
LaMarcus Aldridge was supposed to miss six to eight weeks due to a thumb injury but has decided to put off the surgery.
The Wizards continue their road trip against Kevin Durant and the Thunder.
Beal (toe) and Nene (ankle) left Dallas with minor injuries.
Over the last two games, Humphries has posted 32 points and 15 rebounds in 43 minutes.
It took 27 games, but the Wizards finally played with their projected starting lineup on Christmas.
Seraphin scored 16 points in a season-high 28 minutes.
Big man has come off the bench since returning from plantar fasciitis in his right foot.
With Nene back, the Wizards seek to beat the Magic for the third time this season.