I personally am not a huge fan of the direction of the DCEU so... I'm making my own "Chapter 1" (since gods & monsters wouldn't work so well)
First this DCEU is still starting in 2013... Or is it? Because "Constantine" 2005 would be retconned to be canon (confirmed in like maybe 2012?) and 2011 "Green Lantern" (imagine the ENTIRE movie but 1. No yellow lanterns tease, 2. Parallax is the main villain with a more comic accurate design, 3. Hector Hammond is still the secondary villain but done better and 4. Amanda Waller is probably played by Viola Davis and more comic accurate.) would jump start the DCEU like it was supposed to originally. This DCEU would take breaks between 2005 & 2011 and 2011 & 2013
"Chapter 1"
2005: "Constantine", the exact same.
2011: "Green Lantern", movie is done better and in case you didn't read up top, there isn't the Sinestro tease in the end credits, Parallax is the main villain still with a more comic accurate design, Hector Hammond is done better and Amanda Waller is more comic accurate and played by Viola Davis, the studio and director would treat Ryan Reynolds better and wouldn't make it h3ll for him (from what I've heard) so, he'd be more willing to return and pretend the movie did better than real life.
2012: Constantine (2005) is confirmed as DCEU canon but everything else isn't (besides GL)
2013: "Man of steel" which wouldn't be like the film and instead it would be more comic accurate, an origin story, Lex makes Bizarro after Superman loses a strand of hair fighting inter gang (the members from MAWS along with Frederick Von Frankenstein) and Lex Luthor played by a better actor would be the villain behind the scenes as Brainiac who's too far away from Earth would help Lex clone Supes but Brainiac would make it so Bizarro physically and mentally degrades over time because Brainiac wants to study Superman before attacking.
"The Batman" which is based off a death in the family, has Robert Pattinson taking the lead as Batman with Jason Todd as they go up against Joker & Ra's al Ghūl but Jason dies by Joker which sends Bruce spiraling.
2014: "The Flash" starring Aaron Taylor-Johnson as Wally West taking up the mantle after Flash (Grant Gustin, WB would approach him before CW does) dies and the main villain is Zoom
"Aquaman" starring Alan Ritchson and Elena Satine but this isn't connected to Smallville, is a mix between JL: throne of Atlantis film and the 2018 Aquaman film with it being an origin story, Mera sent by King Nereus (who sided with ocean master, Nereus dies by Arthur) to kill Aquaman but she would fall for him instead and Ocean Master would've killed Atlanna to take the throne
2015: "Green Lantern: Emerald Knight" hal Hal fighting Sinestro and Atrocitus with Carol Ferris becoming a Star Sapphire with a cameo from Aga'po. Ganthet and Sayd would also get kicked out of the guardians at the end.
"Superman/Batman: public enemies" based off Superman/Batman vs the DC universe. Bruce is more violent after the death of Jason and Metallo (unlike in the comic) would've killed Bruce's parents as a mid to late teen and Lex would be running for president and of course loses.
2016: "Man of tomorrow" has Supergirl (Melissa Benoist or Sasha Calle) coming to Earth, Brainiac showing his face (probably played by Blake Ritson) and fights Superman but loses.
"Titans" has the original members being Dick Grayson now Nightwing played by Brenton Thwaites who is like the Titans show, Wally West now Flash, Donna Troy as Wonder girl played by Conor Leslie, Ryan Potter as Beast boy and Cyborg played by Joivan Wade who are now Titans who meet Raven (played by Sophia Lillis or Raffey Cassidy, Nightwing meets her first nearly the same way as the show) and Starfire also comes (played by Anna Diop) to Earth but knows why and tries to kill Raven but sides with the others and gets a romantic relationship with Dick and they fight Trigon voiced by Seamus Dever or Jon Bernthal or even John DiMaggio (I personally prefer either) who is the main villain and same goal as the titans show
2017: "Wonder Woman" which is nearly identical to the real DCEU film but it's not a big flashback and Dr Poison temporarily gets the powers of Diana but "dies", Wonder Woman gets the god killer sword in a labyrinth where she fights then befriends Ferdinand and Ares is played by a better actor and stars Adrianne Palicki or another actress (never a big fan of Gal Gadot) and even with the god killer sword she spares Ares and Steve Trevor still dies.
"The Batman: a lonely place of dying" is based off the comic, Bruce is losing his edge, getting more violent, two-face is the main villain and Tim Drake is introduced (same origin as the new btas adventures) and while Bruce doesn't let Tim become Robin he can't stop him from becoming Red Robin.
2018: "Justice League" has the team forming by Martian Manhunter to warn them that a new team of heroes called Hyperclan aren't good and they fight with the members being: Martian Manhunter, Batman, Wonder Woman, Supergirl, Superman, Hal Jordan, Aquaman, Wally West and John Constantine who appears later.
"Green Arrow" featuring his origin story and based off the comic "Green Arrow: year one" and of course another actor since this DCEU is just replacing the real DCEU, there are still Elseworlds and the arrow verse and the MCU and ECT.
please tell me your feedback and what you think, thanks